It's All About Mainframes..!

What is ERP ?

2011-02-27T19:35:00.003+05:30

Enterprise resource planning (ERP) integrates internal and external management information across an entire organization, embracing finance/accounting, manufacturing, sales and service, etc. ERP systems automate this activity with an integrated software application. Its purpose is to facilitate the flow of information between all business functions inside the boundaries of the organization and manage the connections to outside stakeholders.

ERP systems can run on a variety of hardware and network configurations, typically employing a database to store data.

ERP systems typically include the following characteristics:

An integrated system that operates in (next to) real time, without relying on periodic updates.
A common database, that supports all applications.
A consistent look and feel throughout each module.
Installation of the system without elaborate application/data integration by the Information Technology (IT) department.

Important Areas where they are applied:

Finance/Accounting: General ledger, payables, cash management, fixed assets, receivables, budgeting, consolidation
Human resources: payroll, training, benefits, 401K, recruiting, diversity management
Manufacturing: Engineering, bill of materials, work orders, scheduling, capacity, workflow management, quality control, cost management, manufacturing process, manufacturing projects, manufacturing flow, activity based costing, Product lifecycle management
Supply chain management: Order to cash, inventory, order entry, purchasing, product configurator, supply chain planning, supplier scheduling, inspection of goods, claim processing, commissions
Project management: Costing, billing, time and expense, performance units, activity management
Customer relationship management: Sales and marketing, commissions, service, customer contact, call center support
Data services: Various "self–service" interfaces for customers, suppliers and/or employees
Access control: Management of user privileges for various processes

This is were we are heading...!

2010-02-23T22:45:00.000+05:30

The Shepherd and the Consultant

A shepherd was herding his flock in a remote pasture when suddenly a brand-new BMW advanced out of the dust cloud towards him. The driver, a young man in a Broni suit, Gucci shoes, Ray Ban sunglasses and YSL tie, leaned out the window and asked the shepherd,..........

"If I tell you exactly how many sheep you have in your flock, will you give me one?"

The shepherd looked at the man, obviously a yuppie, then looked at his peacefully-grazing flock and calmly answered, "Sure."

The yuppie parked his car, whipped out his IBM Thinkpad and connected it to a cell phone, then he surfed to a NASA page on the internet where he called up a GPS satellite navigation system, scanned the area, and then opened up a database and an Excel spreadsheet with complex formulas. He sent an email on his Blackberry and, after a few minutes, received a response. Finally, he prints out a 130 page report on his miniaturized printer then turns to the shepherd and says,.........

"You have exactly 1586 sheep".

"That is correct; take one of the sheep" said the shepherd.

He watches the young man select one of the animals and bundle it into his car.

Then the shepherd says: "If I can tell you exactly what your business is, will you give me back my animal?"

"OK, why not" answered the young man.

"Clearly, you are a consultant" said the shepherd.

"That's correct" says the yuppie, "but how did you guess that?"

"No guessing required" answers the shepherd. "You turned up here although nobody called you. You want to get paid for an answer I already knew, to a question I never asked, and you don't know crap about my business.... Now give me back my dog".

JCL Interview Questions

2010-02-21T13:25:00.001+05:30

JCL INTERVIEW QUESTIONS

JCL QUESTIONS SET 1

1. What is primary allocation for a Data Set?

The space allocated when the Data Set is first created

2. What is the difference between primary and secondary allocations for a Data Set?

Secondary allocation is done when more space is required than what has already been allocated

3. How many extents are possible for a Sequential File ? For a VSAM File ?

16 extents on a volume for a Sequential File and 123 for a VSAM File

4. What does a disposition of (NEW,CATLG,DELETE) mean?

- That this is a new Data Set and needs to be allocated, to CATLG the Data Set if the step is successful and to delete the Data Set if the step abends.

5. What does a disposition of (NEW,CATLG,KEEP) mean?

- That this is a new Data Set and needs to be allocated, to CATLG the Data Set if the step is successful and to KEEP but not CATLG the Data Set if the step abends Thus if the step abends, the Data Set would not be catalogued and we would need to supply the Vol ser the next time we refer to it

6. How do you access a File that had a disposition of KEEP?

- Need to supply volume serial no VOL=SER=xxxx MOD,DELETE

7. What does a disposition of (,DELETE) mean ?

The MOD will cause the Data Set to be created (if it does not exist), and then the two DELETE will cause the Data Set to be deleted whether the step abends or not This disposition is used to clear out a Data Set at the beginning of a job

8. What is the DD statement for a output File?

Unless allocated earlier, will have the following parameters: DISP=(NEW,CATLG,DELETE), UNIT , SPACE & DCB

9. What do you do if you do not want to keep all the space allocated to a Data Set?

Specify the parameter RLSE ( release ) in the SPACE. Eg: SPACE=(CYL,(50,50),RLSE)

10. What is DISP=(NEW,PASS,DELETE)?

This is a new File and create it, if the step terminates normally, pass it to the subsequent steps and if step abends, delete it This Data Set will not exist beyond the JCL

11. How do you create a temporary Data Set? Where will you use them?

Temporary Data Sets can be created either by not specifying any DSNAME or by specifying the temporary File indicator as in DSN=&&TEMP We use them to carry the output of one step to another step in the same job The Data Set will not be retained once the job completes

12. How do you restart a proc from a particular step?

In job card, specify RESTART=proc step step name where procstep = name of the jcl step that invoked the proc and stepname = name of the proc step where you want execution to start

13. How do you skip a particular step in a proc/JOB?

Can use either condition codes or use the jcl control statement IF (only in ESA JCL)

14. A PROC has five steps Step 3 has a condition code How can you override/nullify this condition code?

Provide the override on the EXEC stmt in the JCL as follows: //STEP001 EXEC procname,CONDstepname=value All parameters on an EXEC stmt in the proc such as COND, PARM have to be overridden like this

15. How do you override a specific DDNAME/SYSIN in PROC from a JCL?

// DSN=

16. What is NOTCAT 2?

This is an MVS message indicating that a duplicate catalog entry exists Eg, if you already have a Data Set with dsn = 'xxxxyyyy' and u try to create one with disp new,catlg, you would get this error the program open and write would go through and at the end of the step the system would try to put it in the system catalog at this point since an entry already exists the catlg would fail and give this message you can fix the problem by deleting/uncataloging the first data set and going to the volume where the new Data Set exists(this info is in the msglog of the job) and cataloging it

17. What is 'S0C7' abend?

Caused by invalid data in a numeric field

18. What is a S0C4 error ?

Storage violation error - can be due to various reasons eg: READING a File that is not open, invalid address referenced due to subscript error

19. What are SD37, SB37, SE37 abends?

All indicate Data Set out of space. SD37 - no secondary allocation was specified. SB37 - end of vol and no further volumes specified. SE37 - Max of 16 extents already allocated

20. What is S322 abend ?

Indicates a time out abend Your program has taken more CPU time than the default limit for the job class Could indicate an infinite loop

21. Why do you want to specify the REGION parameter in a JCL step?

To override the REGION defined at the JOB card level REGION specifies the max region size REGION=0K or 0M or omitting REGION means no limit will be applied

22. What does the TIME parameter signify ? What does TIME=1440 mean ?

TIME parameter can be used to overcome S322 abends for programs that genuinely need more CPU time TIME=1440 means no CPU time limit is to be applied to this step

23. What is COND=EVEN ?

Means execute this step even if any of the previous steps, terminated abnormally

24. What is COND=ONLY ?

Means execute this step only if any of the previous steps, terminated abnormally

25. How do you check the syntax of a JCL without running it?

TYPERUN=SCAN on the JOB card or use JSCAN

26. What does IEBGENER do?

Used to copy one SAM File to another Source Data Set should be described using SYSUT1 ddname Destination Data Set should be decribed using SYSUT2 IEBGENR can also do some reformatting of data by supplying control cards via SYSIN

27. How do you send the output of a COBOL program to a member of a PDS?

Code the DSN as pds(member) with a DISP of SHR The DISP applies to the pds and not to a specific member

28. I have multiple jobs ( JCLs with several JOB cards ) in a member What happens if I submit it?

Multiple jobs are submitted (as many jobs as the number of JOB cards)

29. I have a COBOL program that ACCEPT some input data How do you code the JCL statement for this? ( How do you code instream data in a JCL?

) //SYSIN DD* input data input data /*

30. Can you code instream data in a PROC ?

31. How do you overcome this limitation ?

One way is to code SYSIN DD DUMMY in the PROC, and then override this from the JCL with instream data

32. How do you run a COBOL batch program from a JCL? How do you run a COBOL/DB2 program?

To run a non DB2 program, //STEP001 EXEC PGM=MYPROG To run a DB2 program, //STEP001 EXEC PGM=IKJEFT01 //SYSTSIN DD * DSN SYSTEM() RUN PROGRAM(MYPROG) PLAN() LIB() PARMS() /*

33. What is STEPLIB, JOBLIB? What is it used for?

Specifies that the private library (or libraries) specified should be searched before the default system libraries in order to locate a program to be executed STEPLIB applies only to the particular step, JOBLIB to all steps in the job

34. What is order of searching of the libraries in a JCL?

First any private libraries as specified in the STEPLIB or JOBLIB, then the system libraries such as SYS1LINKLIB The system libraries are specified in the linklist

35. What happens if both JOBLIB & STEPLIB is specified ?

JOBLIB is ignored

36. When you specify multiple Data Sets in a JOBLIB or STEPLIB, what factor determines the order?

The library with the largest block size should be the first one 37. How to change default proclib ?

//ABCD JCLLIB ORDER=(MEMYPROCLIB,SYS1PROCLIB)

38. The DISP in the JCL is MOD and the program opens the File in OUTPUT mode What happens ?

The DISP in the JCL is SHR and the pgm opens the File in EXTEND mode What happens ?

Records will be written to end of File (append) when a WRITE is done in both cases

39. What are the valid DSORG values ?

PS - SAM, PO - Partitioned, IS - ISAM

40. What are the differences between JES2 & JES3 ?

JES3 allocates Data Sets for all the steps before the job is scheduled. In JES2, allocation of Data Sets Required by a step are done only just before the step executes. JOB /EXEC/DD ALL PARAMETERS JOBLIB/STEPLIB PROCEDURES, PARAMETERS PASSING CONDITION VARIABLES ABEND CODES.

41. What are the kinds of job control statements?

The JOB, EXEC and DD statement

42. What is the meaning of keyword in JCL?What is its opposite?

A keyword in a JCL statement may appear in different places and is recognized by its name, eg MSGCLASS in the JOB statement The opposite is positional words, where their meaning is based on their position in the statement, eg in the DISP keyword the =(NEW,CATLG,DELETE) meaning are based on first, second and third position.

43. Describe the JOB statement, its meaning, syntax and significant keywords.?

The JOB statement is the first in a JCL stream Its format is // jobname, keyword JOB, accounting information in brackets and keywords, MSGCLASS, MSGLEVEL, NOTIFIY, CLASS, etc .

44. Describe the EXEC statement, its meaning, syntax and keywords.?

The EXEC statement identifies the program to be executed via a PGM=program name keyword Its format is //jobname EXEC PGM=program name The PARM= keyword can be used to pass external values to the executing program.

45. Describe the DD statement, its meaning, syntax and keywords.?

The DD statement links the external Data Set name (DSN) to the DDNAME coded within the executing program It links the File names within the program code to the File names know to the MVS operating system The syntax is // ddname DD DSN=Data Set name Other keywords after DSN are DISP, DCB, SPACE, etc .

46. What is a PROC?What is the difference between an instream and a catalogued PROC?

PROC stands for procedure It is 'canned' JCL invoked by a PROC statement An instream PROC is presented within the JCL; a catalogued PROC is referenced from a proclib partitioned Data Set.

47. What is the difference between a symbolic and an override in executing a PROC?

A symbolic is a PROC placeholder; the value for the symbolic is supplied when the PROC is invoked, eg &symbol=value An override replaces the PROC's statement with another one; it substitutes for the entire statement

48. What is RESTART? How is it invoked?

A RESTART is a JOB statement keyword It is used to restart the job at a specified s step rather than at the beginning

49A. What is a GDG? How is it referenced?How is it defined? What is a MODELDSCB?

GDG stands for generation data group It is a Data Set with versions that can be referenced absolutely or relatively It is defined by an IDCAMS define generation datagroup execution

49B. Explain concatenating Data Sets ?

Data Sets can be grouped in a DD statement one after another, eg in a JOBLIB statement where the load module can exist in one of many Data Sets.

49C. What is the difference between specifying DISP=OLD and DISP=SHR for a Data Set?

A DISP=OLD denotes exclusive control of the Data Set; DISP=SHR means there is no exclusivity .

50. What is MOD and when would you use it?

DISP=MOD is used when the Data Set can be extended, ie, you can add records at the end of an existing Data Set

51. What are the keywords associated with DCB? How can you specify DCB information? What is the OS precedence for obtaining that DCB information, ie where does the system look for it first?

The keywords associated with the DCB parameter are LRECL, RECFM, BLKSIZE and DSORG The DCB information can be supplied in the DD statement The system looks for DCB information in the program code first

52. How do you designate a comment in JCL?

The comment statement is //* followed by the comments.

53. What is the meaning of the EXEC statement keyword, COND? What is its syntax?

COND specifies the conditions for executing the subsequent job step The value after the COND= is compared to the return codes of the preceding steps and if the comparison is true, the step is bypassed (If this answer confuses you, welcome to the club - memorize it and don't ask questions!).

54. What is the improvement to COND= in the latest version of MVS?

MVS now allows for an IF bracketed by an END IF around any job step to replace the COND= syntax Again, if the IF statement is true, the step is bypassed.

55. What is the purpose of the PARM keyword in the EXEC statement?

The value after the PARM= specifies control information to be passed to the executing program of the job step

56. What is the purpose and meaning of the REGION keyword and what JCL statement is it associated with?

REGION specifies the maximum CPU memory allocated for a particular job or job step If REGION is in the JOB card, it relates to the entire job; if in the EXEC statement, it relates to the job step .

57. What is the purpose and meaning of the TIME keyword and what JCL statement is it associated with?

TIME specifies the maximum CPU time allocated for a particular job or job step If TIME is in the JOB card, it relates to the entire job; if in the EXEC statement, it relates to the job step.

58. What is the meaning of data definition name (DD name) and Data Set name (DSN name) in the DD statement?

Data definition name is the eight character designation after the // of the DD statement It matches the internal name specified in the steps executing program In COBOL that's the name specified after the ASSIGN in the SELECT ASSIGN statement Data Set name is the operating system (MVS) name for the File

59. How is the keyword DUMMY used in JCL?

For an output File DUMMY specifies that the output is to be discarded For input it specifies that the File is empty.

60. What does the keyword DCB mean and what are some of the keywords ?

associated IT DCB stands for data control block; it is a keyword for the DD statement used to describe Data Sets Keywords associated with it are BLKSIZE, DEN, LRECL and RECFM.

61. What is the difference between BLKSIZE and LRECL?

BLKSIZE specifies the number of bytes

62. What are all the JCL statements used in JCL? & What are the JCL statements you have coded so far?

//JOB marks the beginning of a job, contains job information //EXEC marks the beginning of a job step, identifies program, cataloged procedure to be executed //DD (data definition), identifies a data set and its attributes //OUTPUT (specifies processing options for system output(sysout) data sets) //(null) (end of job) /* (end of data placed in input stream) //PROC (procedure) //PEND (procedure end) //* (comment)

63. What is the difference between the positional parameters & keyword parameters, give examples where they are used?

Positional Parameters are:- a).Sequence predetermined b) Parameters separated by commas c) Omitted parameters must be indicated by two consecutive commas. d) Installation dependent EX: //JOBNAME JOB (DIS, TRG.TRGGLO.NL.BATCH), ‘PGM1) //SETP01 EXEC PGM=MYPROG Keyword parameters are Predetermined words are referred to as key word Parameters. Any sequence is permitted, separated by commas. Follow positional parameters. Format is = EX: //JOBNAME JOB (DIS, TRG, N1, BATCH), MSGLEVEL=(1,1), // MSGCLASS=X, NOTIFY=QZ6P03T, TYPRUN=SCAN

64. What are the operands coded in a JOB statement?

All the Positional and Key word parameters in the JOB statement. Accounting Information, MSGCLASS, CLASS, MSGLEVEL, NOTIFY, USERID, PASSWD, COND, REGION, RESTART.

65. How many characters can be coded for a job name? What were you coding as a job name?

8 Characters, Usually JOBNAME will be like User-id + 1 Char

66. What is the difference between the Comment statement and the Comments?How they were coded in a JCL?

//* is the comment statement and it starts from column number 1 Anything that is written after 71st column is taken as a comment.

67. How will you check the syntax of the JOB without executing it?

Can use JSCAN.Code TYPRUN=SCAN and submit the JCL for syntactical errors.

68. What are all the parameters needed in a DD statement to create a data set thru JCL? How a Partitioned data set is created thru JCL?

DISP (Disposition): The DISP parameter describes the status of a data set to the system, what is to be done with the data set at the end of the job step, and what to do with the data set if the step terminates abnormally DCB (Data control black) : DCB=(LRECL=NN, BLKZIZE=YY,RECFM=Z,DSORG=MM) Z can be F, FB, V, VB MM Can be PS (physical sequence) PO (partitioned) DSN (Data set name) : UNIT : Identifies device of data set Space :

69. How is the Catalog procedure called from a JCL, if it is lying in your own data sets ?

STEP1 EXEC PROC=PROC1 The library in which PROC1 is present should be mentioned in PROCLIB.

70. What is the difference between the In-stream Procedure & Catalog Procedure?

In-stream Procedures begin with a PROC stmt and must be terminated by a PEND stmt. (PEND can also be coded for a cataloged Procedure, but it isn’t required) The PENC stmt coded as : //Option-name PEND comments The In-stream Procedure is placed following the JOB statement of the JOB. Up to 15 In-stream Procedures can be included in a single job. Each In-stream Procedure may be invoked several times with in the job. //QZ5P13TD JOB (18636), ‘HARISH’, CLASS=A //RUN PROC In-stream procedure starts from here //GO EXEC PGM=ONE //SYSOUT DD SYSOUT=A //PEND //STEP1 EXEC RUN procedure is used like .. A set of JCL stmt’s consisting of a PROC stmt and one or more EXEC and DD stmt (steps), which is placed in a procedure library. It executed by an EXEC (procedure) stmt in another data set (called the execution JCL). Advantages : Saves time, prevents errors.

71. What is the Symbolic parameter?

What for it is needed? Where it is most commonly used?

Any parameter that can vary with each execution is a good candidate for definition of a symbolic parameter. Use of symbolic parameter make the procedure more flexible. This prevents the procedure to be modified each and every time a small and recurring change is needed at a place. //DD1 DD DSNAME=&SYSUID..PROFILE,DISP=(NEW,KEEP),

72. Can you explain the DISP Parameter in detail? What are the default DISP Parameters?

a. Current Status NEW – Default OLD – exclusive SHR – Simultaneously MOD – b. Normal Disposition KEEP – Default if DISP = SHR, OLD, MOD DELETE – Default if DISP = NEW CATLG c. Abnormal Termination – same as Normal Disposition

73. What is the difference between the Refer-back & Overriding parameters?How are they coded in a JCL?

Refer back option is a reference to an earlier DD statement in the job or in cataloged or in in-stream procedure called by a job step. KEYWORD = reference. //JOB1 JOB .. //STEPA EXEC .. //DD1 DD DSN=REPORT ... // DD4 DD DSN=*.DD1 //JOB2 JOB .. //SETP1 EXEC .. //DDA DD DSN=D578.POL.PUBS01 .. //STEP2 EXEC .. //DDB DD DSN=*.STEP1.DDA Over riding parameters. In an In-stream or Cataloged procedures, the DD names mentioned in the JCL will override the ones in the procedures. //JOB1 JOB .. //STEPA EXEC PROC1 //PS1.DD1 DD DSN=SAMPLE.PUB,DISP=SHR //PS2.DD2 DD DSN=SAMPLE.PUB1,DISP=SHR Proc PROC1 contains... //PS1 EXEC PGM=ABC //* //DD1 DD DSN=DUMMY //SYSOUT DD SYSOUT=* // //PS2 EXEC PGM=DEF //* //DD1 DD DSN=SAMP.PROG.DATA,DISP=SHR //DD2 DD DSN=SAMP.PROG.DATA1,DISP=SHR // SYSOUT DD SYSOUT=*

74. How do you pass parameters to a program coded in an EXEC statement?

Through PARM Clause coded on the EXEC statement. The parameters have to be defined in the Linkage Section of COBOL program.

75. What is a GDG?<>

A GDG is Generation Data Group. GDG’S allow users to create multiple data sets with the same base name distinguished by a logical number. History files can be referenced by using a negative generation number. GDG base can be created using a utility (IEBPROGM or IDCAMS) With (+1) we will be creating. EX: //OUTDD DD DSN=QZ6P03T.ARUN.MASTER(+1) (Create new data set) //INDD DD DSN=QZ6P03T.ARUN.MASTER(+0) (Reference most current data set). Yes - GDG can be sequential, direct, or partitioned Organization and can be reside on tape or direct-access volumes GDG must always be cataloged

76. What are the parameters used in creating a GDG? Explain in detail? Can you alter the parameters for the existing GDG?If yes, How?

Creating a Model Data Set Label (or control block, DSCB) This label is a data set which contains DCB attributes and is usually referred to in the DCB parameter when creating new GDG data sets. Most shops create the model DSCB with no DCB attributes.

77. What for the Model data set used for a GDG? How much space will you give to the Model Data set ?

The system needs an existing data set to serve as a model supplying the DCB parameters for the GDG to you want to create. The system uses the data set label to obtain the DCB sub-parameters, and the model is called the DSCB for reasons lost to history. Need not specify any space while creating a model data set.

78. How many Maximum generations can be created for a GDG?> How will you create a Generation data set ?

The maximum number of GDG versions that can be created is 255. A GDG data set is created with “(+1)” appended to the name of the GDG base.

79. What is the E37 error?How will you resolve it with out losing a single byte of data?

(Hint: This Error comes when you save the data set after editing it) Insufficient Space.

80. What is SOC7 abend ?How do you resolve it?

Data Exception. Eliminate the bad data by debugging the program.

JCL QUESTIONS SET 2

Q: What are S0C1, S0C4, S0C5, S0C7 ABENDs??

A: S0C1 (Operation Exception Error) - May be due to

Missing or misspelled DD name

Read/Write to unopened dataset

Reading a dataset opened output mode

Writing into a dataset opened input mode

Called subprogram not found

S0C4 may be due to

Missing Select statement (during compile)

Bad Subscript/index

Protection Exception

Missing parameters on called subprogram

Read/Write to unopened file

Move data from/to unopened file;

S0C5 May be due to

Bad Subscript/index

Close an unopened dataset

Bad exit from a perform

Access to I/O area (FD) before read;

S0C7 may be due to

Numeric operation on non-numeric data

Un-initialized working storage

Coding past the maximum allowed subscript

S0CB might be due to 1.Division by Zero

Q: Why do you use a CONTROL CARD?

A: A CONTROL CARD can be a member of a PDS or a sequential dataset and is used for storing the date fields, definitions of VSAM files etc., We use CONTROL CARD because we cannot use an in-stream procedure in a procedure. Generally you will be calling a PROC from your JCL and you cannot code instream procedure in the PROC and so you will point to the dataset, which is called controlcard.

Q: How do you submit JCL via a Cobol program?

A: In your JCL define as: //JOBA JOB 1111,JOB1 //STEP01 EXEC PGM=PROG1 //ddname DD SYSOUT=(*,INTRDR)....and your COBOL (PROG1) should look like this: SELECT JCL-FILE ASSIGN TO ddname. Open this file and write the JCL statements into this file. Example: MOVE '//TESTJOB JOB 1111,VISVEISH' TO JCL-REC.MOVE '//STEP01 EXEC PGM=IEFBR14' TO JCL-REC.and close this file. Then TESTJOB will be submitted.

Q: How do you submit a JCL under CICS environment?

A: Pass all the JCL codes to a COBOL variable (should be declared using OCCURS clause) and then write the line one by one to the spool using CICS commands like SPOOLClose, SPOOLOpen and SPOOLWrite. For more help refer CECI of CICS or CICS manual.

Q: What is the parameter to be passed in the job card for the unlimited time, irrespective of the job class

A: TIME=1440

Q: Define COND parameter in JCL?

A: COND is a condition parameter, consists of 2 subparameters, 1st - return code from the previous step, 2nd - condition. If COND is true, the step on which COND is coded will be BYPASSED. It is compared with system return code of previous step //STEP1 EXEC PGM=ABCD //STEP2 EXEC PGM=XYZ, cond=(4,lt) STEP 2 will be executed when system return code of step1 is less than 4.

Q: What is meant by S0C-07 system ABEND codes

A: S0C7 - Data exception error - you will get it whenever you are trying to move the low values or spaces into the numeric field, or compare the numeric fields with low values, or try to do some arithmetic operations on the low values. To avoid this you have to always initialize the numeric fields otherwise they will contain the low values.

Q: How to pass the temp dataset form one JOB step to another?

A: By specifying the DISP as PASS for the temp dataset

Q: Write a JCL to execute a Job by 7:00 AM on Jan 20,1986?

A: The code is: //*MAIN DEADLINE=(0700,B,012086)

Q: How many types of libraries are there in JCL?

A: Libraries are of three types: System Libraries:- such as SYS1.LINKLIB Private Libraries:- Specified in a JOBLIB or STEPLIB DD STATEMENTS. Temporary Libraries:- Created in a previous step of the Job.

Q: What do you mean by INCLUDE statement in JCL?

A: An INCLUDE statement identifies a member of a PDS that contains this set of JCL statements is called an INCLUDE group. The system replaces the INCLUDE statement with the statements in the INCLUDE group.

Q: What are the Maximum number of In-stream procedures you can code in any JCL?

A: 15.

Q: What you mean by skeleton JCL?

A: JCL, which changes during run time,that is the values for the JCL such as program name, dd name will change. The same JCL can be used for various jobs, equivalent to dynamic SQL;

Q: What is JCL

A: It is an interface between operating system (MVS) & the application program. When two related programs are combined together on control statements, it is called job control language

Q: What is the maximum blocksize for a Tape file?

A: It is 32,760. Based on that we can calculate efficient number of Records in a Block

Q: What are the basic JCL Statements for a Job?

A: The basic JCL statements for any job are: JOB : Identifies a job and supplies accounting info EXEC : Identifies a job step by indicating the name of the program to be executed. DD : Identifies a data set to be allocated for the job step Delimiter (/*) : Marks the end of an in-stream dataset Null (//) : Marks the end of a job Comments (//*) : Provides Comments PROC : Marks the beginning of a procedure PEND : Marks the end of a procedure OUTPUT : Supplies options for SYSOUT processing.

Q: What does the statements: TYPRUN=SCAN and TYPRUN=HOLD do in a JCL statement?

A TYPRUN= SCAN checks the JCL for errors, TYPRUN= HOLD holds the job until further notice.

Q: What is QSAM error usually when it occurs?

A: Usually it occurs at the time of job submission.

Q: What is the purpose of INCLUDE statement in a JCL?

A: It is used as an alternative for STEPLIB. When we specify the dataset name in INCLUDE , it will search in all the datasets specified in the INCLUDE dataset.

Q: Is it possible to know the remaining free space in a Control Interval/Control Area once an insertion has been made

A: No. It is not possible.

Q: What does SOC-04 error mean?

A: This error is faced when we execute the Cobol program. The main reason for this error is that a variable is defined with fewer characters and we are trying to move data, which is larger than the actual storage space.

Q: In which table PLAN is registered in?

A: RCT

Q: What is a GDG?

A: GDG - group of dataset that are logically or chronologically related, referred by name and a relative generation number - an integer which identifies the generation of a dataset and is coded in parentheses after dataset name. Absolute GDG name - GxxxxVyy, where xxxx-absolute generation number, yy-version number. GDGs can be sequential, direct, partitioned. (VSAM - no). They must always be cataloged. Advantages - all datasets have the same name and system keeps track of adding new and retaining previous generations and deleting oldest successive generation. To create a GDG we create a GDG index in the system catalog with IDCAMS utility and then a model (prototype, DSCB) on the same volume to supply DCB information. Empty - when limit is reached all members are removed from the index, otherwise only oldest. Scratch-removed members are uncataloged & deleted, otherwise - removed & uncataloged, but remain in the system (not members of GDG any more). GDG number is updated at the end of the job. If number is not specified all generations will be processed from the beginning

Q: What do you mean by spooling?

A: This is managed by JES. This is used for Queuing the Outputs that are intended for Printing and are first stored in SPOOLDASD.

Q: How many Instream-Procedures (PROCs) can be coded in a single Job?

A: 15

Q: For how long a Job can be executed continuously on a Mainframe?

A: 248 DAYS

Q: How may divisions are there in JCL-COBOL?

A: SIX

Q: What is the Maximum number of DD Statements to be coded in a single JCL

A: 3273

Q: How much space OS allocates when you create a PS or PDS?

A: 56 KB

Q: What is the minimum number of Dataset names (PDS) in one Directory Block?

A: SIX

Q: What is the maximum number of steps in a Job?

A: 255

Q: How much is memory space involved, when we code BLOCKSIZE, TRK & CYL

A: One block constitutes 32KB of formatted memory/ 42KB of Unformatted memory; 6 blocks makes one Track & 15 Tracks makes one cylinder.

Q: What is DSNDB06?

A: This is the Place where DB2 Catalog resides;

Q: What is the use of DSNDB07?

A: This is the area where sorting takes place in DB2

Q: What is DATACOM DB?

A: It is a Database used with VSE.

Q: What is a Dummy Utility and what it does?

A: IEFBR14 is a Dummy utility and it is used for the sakeof EXEC PGM= .... statement in JCL [when used it wouldn’t perform any task]. e.g. While Allocating a dataset you don't have to run any utility [this could be done by giving disp=new in DD statment]. But for a PGM name must be given in EXEC statment, it is used.

Q: What 3 guidelines do we have to follow when concatenating DD statements?

A: The three guidelines for concatenating DD Statements are:- Datasets must be of the same type (disk or tape) All datasets must have the same logical record length (LRECL) The dataset with the largest blocksize must be listed first.

Q: On a DD statement, what is the main difference between creating a new sequential flat file and a partitioned dataset?

A: SPACE= (n,m) for a sequential file, SPACE= (n,m,p) for a PDS where n, m, and p are numbers. The p designates how many directory blocks to allocate.

Q: What is the difference between IEBGENER, IEBCOPY and REPRO in IDCAMS utility?

A: They are the utility programs used in JCLs: IEBGENER : This utility is used for copying sequential datasets which produces a PDS or a member from a sequential dataset. IEBCOPY : This utility is used for copying one PDS to another or to merge PDSs. REPRO : This is for copying sequential datasets. More or less same as the IEBGENER

Q: What is the difference between STATIC CALL & DYNAMIC CALL

A: In the case of STATIC CALL, the called program is stand-alone and an executable. During run time we can call it in our called program. In a DYNAMIC CALL, the called program is not an executable program and it can executed through the called program

Q: What is the difference between CATALOGED PROCEDURE and IN-STREAM PROCEDURE?

A: INSTREAM PROCEDURES are set of JCL statements written between JOB and EXEC statements, start with PROC and end with PEND statement. Mainly used to test cataloged procedures. CATALOGED PROCEDURES are cataloged on the procedure library (PROCLIB) and is called by specifying the procedure name on the EXEC statement.

Q: Can we browse or edit the GDG dataset if it is a tape entry?

A: No

Q: What are the maximum and minimum sizes of any CONTROL AREA (VSAM datasets)?

A: Minimum Size : 1 track; Maximum size : 1 cylinder

Q: How many parameters are there to a DISP statement and what are their uses. ?

A: There are three (3) parameters: Parameter 1: Current data set disposition (NEW, SHR,OLD,MOD) Parameter 2: Normal close action for data set (CATLG, KEEP, DELETE) Parameter 3: Abend action for data set (CATLG, KEEP, DELETE)

Q: What is COMP?

A: COMP - HALF WORD BINARY

Q: What is a PROCEDURE?

A: A set of precoded JCL that can be modified through the use of parameters or override cards. Note: Procedures can be catalogued or instream.

Q: What is the difference between specifying DISP=OLD and DISP=SHR for a dataset?

A: OLD specifies exclusive use of a dataset, SHR allows multiple jobs to concurrently access the dataset. [Note: When updating a dataset, you would normally use OLD]

Q: What are the three basic types of statements in a jobstream?

A: The three basic types of statements in a jobstream are: JOB : We can code one per jobstream EXEC : It can be one or more per job DD : one or more per jobstep); JOB – It indicates start of jobstream to the operating system and through parms coded on it, it contains certain details about the job (like time, region, message level, job accounting data). EXEC – It indicates the start of execution of a particular job step, be that step a program or a proc. DD – It is a data definition statement, which is used to describe the attributes of a dataset (like name, unit, type, space, disposition etc.,).

Q: What does SYSIN * indicate?

A: Instream data follows this card and is terminated when followed by a card containing // or /* in columns 1 and 2.

Why Mainframe cannot be Hacked ?

2010-02-17T23:31:00.001+05:30

Windows is an operating system started off as being meant for one user only, and they could run only one program at a time, and it was written to manage real devices in the PC, that is, it was limited to what the PC had ( eg.,640K).

When it was realised that this approach meant that programs which required more hardware capacity (like memory) could not be written, special routines that virtualised hardware had to be written. However, the underlying operating system files etc were all open to anyone who wanted to install software, that is, any programmer could overwrite system software causing malicious or unintended damage.The operating system grew organically and tries to mimic multi- user environment, virtualisation and allowing multiple programs at the same time etc, but this has been developed as additions and not designed from ground up. Hence the stability issues and issues of hacking because the entire system software etc was open for anybody to overwrite with their own code.

Mainframe OZ (zOS) on the other hand was written ground up to be virtual,multi user system, multi program system. The hardware was always virtualised and programmers do not deal with physical limitations of the system.

Next, Operating system files and production code always was protected by the creation of a strict discipline and the creation of special libraries from which they could be run. This iscontrolled by system programmers.

Application programs never replace operating system files unlike in Windows or UNIX (to a lesser extent).

This created this environment never to be hacked to date.

Role of Production Control Analyst

2010-02-02T07:20:00.002+05:30

The person who ensures that batch workloads run to completion without error or delay

Monitoring online regions like CICS, IMS, DB2

Manage online and batch processing

Scheduling jobs & packages

Providing production support in resolving batch job failures

Managing preventive maintenance schedules

Following right escalation procedure

Maintaining quality documents for reference

Role of System Operator

2010-01-28T11:12:00.003+05:30

The person who monitors and controls the operation of the mainframe hardware and software

Starts and stops the tasks and subsystems

Performs IPL and hardware restart

Works closely with system programmers and Production control analyst to ensure normal operation of the systems

Role of Application Programmer

2010-01-27T08:06:00.002+05:30

Application programmer will design, build, test and deliver mainframe applications based on client/user requirements

The process includes several iterations of code changes and compilation, application builds and unit testing

The programmer is responsible for maintaining and enhancing the company's existing mainframe applications

COBOL, PL/I, REXX, JAVA, C and CLIST are widely used languages

Role of System Administrator

2010-01-25T09:46:00.003+05:30

Adding, deleting users and maintaining user profiles

Maintaining security resource access lists

Managing storage devices and printers

Managing networks and connectivity

Monitoring system performance

Defining & customizing subsystem resources

Defining DB2, CICS & Websphere MQ resources

Role of the System Programmer

2010-01-24T09:26:00.006+05:30

In a mainframe IT organization, the system programmer plays a central role. The system programmer installs, customizes, and maintains the operating system, and also installs or upgrades products that run on the system. The system programmer might be presented with the latest version of the operating system to upgrade the existing systems, or the installation might be as simple as upgrading a single program, such as a sort application.

Planning Hardware & software system upgrades and changes in configuration

Automating operations and capacity planning

Running installation jobs and scripts

Performing installation-specific customization tasks

Integration-testing the new products with existing applications and user procedures

System-wide performance tuning to meet required levels of service

Training system operators and application programmers

History of Mainframe Computer

2010-01-22T08:05:00.003+05:30

1500	Leonardo da Vinci designs a mechanical calculator.
1823	Charles Babbage starts work on his Difference Engine.
1880	Herman Hollerith constructed a punched-card system to automate the U.S. census. He later sold the technology to the company that became IBM.
1906	The vacuum tube is invented by American physicist Lee De Forest.

	The 1st Generation The tube-based mainframe computers
1939	Dr. John V. Atanasoff and his assistant Clifford Berry build the first electronic digital computer. Their machine, the Atanasoff-Berry-Computer (ABC) provided the foundation for the advances in electronic digital computers
1941	Konrad Zuse (recently deceased in January of 1996), from Germany, introduced the first programmable computer designed to solve complex engineering equations. This machine, called the Z3, was also the first to work on the binary system instead of the decimal system.
1942	Vannevar Bush's "Rockefeller Differential Analyzer" -- a one-hundred-ton machine with 2000 vacuum tubes and 150 motors, is dedicated at MIT. Bush's Analyzer was an analog computer as opposed to today's digital computers. A thermostat is a simple analog computer. It was used to calculate ballistic trajectories during W.W.II.
	British Intelligence's Colossus built at Bletchly Park by British mathematician Alan Turing. It was a large-scale electronic machine. The Colossus, a special-purpose machine developed to decode secret messages, performed the logical, as opposed to arithmetical, operations necessary to defeat the famous German code machine Enigma.
1944	Eniac (electronic numerical integrator and calculator ) was placed in operation at the Moore School. By today's standards for electronic computers the ENIAC was a grotesque monster. Its thirty separate units, plus power supply and forced-air cooling, weighed over thirty tons. Its 19,000 vacuum tubes, 1,500 relays, and hundreds of thousands of resistors, capacitors, and inductors consumed almost 200 kilowatts of electrical power. But ENIAC was the prototype from which most other modern computers evolved. Eniac was originally used for ballistics, but played a roll in the development of the atomic bomb.
	Howard Aiken, in collaboration with engineers from IBM, constructed a large automatic digital sequence-controlled computer called the Harvard Mark I. This computer could handle all four arithmetic operations, and had special built-in programs for logarithms and trigonometric functions.
1945	John von Neumann wrote "First Draft of a Report on the EDVAC" in which he outlined the architecture of a stored-program computer. This report changed the direction of computer development away from punched paper tape.
	September 9th, Grace Hopper (one of the creators of the COBOL programming language) recorded the first actual computer "bug" — a moth stuck between the relays and logged at 15:45 hours on the Harvard Mark II.
1947	On December 23, William Shockley, Walter Brattain, and John Bardeen successfully tested this point-contact transistor, setting off the semiconductor revolution
	Bell Labs physicists Shockley, Brattain, and Bardeen create the first Germanium transistor.
1948	Remington engineers complete the Model 3, a one of a kind concept computer.
	GE Electronics Laboratory in Syracuse wins an order for a USAF tube computer, named OARAC.
1951	The first UNIVAC I mainframe computer was delivered to the Census Bureau. Unlike the ENIAC, the UNIVAC processed each digit serially. But its much higher design speed permitted it to add two ten-digit numbers at a rate of almost 100,000 additions per second. Internally. It was the first mass-produced computer. The central complex of the UNIVAC was about the size of a one-car garage: 14 feet by 8 feet by 8.5 feet high. It was a walk-in computer. The vacuum tubes generated an enormous amount of heat, so a high capacity chilled water and blower air conditioning system was required to cool the unit. The complete system had 5200 vacuum tubes, weighed 29,000 pounds, and consumed 125 kilowatts of electrical power.
1952	The Remington (later SperryRand) Model 409 was delivered to the Internal Revenue Service facility in Baltimore.
	MANIAC (mathematical analyzer, numerical integrator and computer) built at Los Alamos by Metropolis. It was responsible for the calculations of Mike, the first hydrogen bomb. It was followed by MANIAC II, the IBM-built STRETCH supercomputer and a series of commercial super computers that have made the Laboratory the world's largest scientific computing center
	The IBM 701 Electronic Data Processing Machine announced by IBM President Thomas J. Watson, Jr. was IBM's first commercially available scientific computer and the first IBM machine in which programs were stored in an internal, addressable electronic memory. It was the first of the pioneering line of IBM 700 series mainframe computers, including the 702, 704, 705 and 709. The computer consisted of two tape units (each with two tape drives), a magnetic drum memory unit, a cathode-ray tube storage unit, an L-shaped arithmetic and control unit with an operator's panel, a card reader, a printer, a card punch and three power units. The 701 could perform more than 16,000 addition or subtraction operations a second, read 12,500 digits a second from tape, print 180 letters or numbers a second, and output 400 digits a second from punched-cards.
1953	IBM's drum memory 650 computer, announced. It sold for $200,000 to $400,000 and was a great success: more than 1800 were sold or leased.. The basic IBM 650 had 2000 words of memory and 60 words of core memory. It was the first computer on which IBM made a meaningful profit.
	First IBM 701 delivered.
1955	IBM 704 announced. It was the first large-scale commercially available computer system to employ fully automatic floating point arithmetic commands. It was a large-scale, electronic digital computer used for solving complex scientific, engineering and business problems and was the first IBM machine to use FORTRAN. The 704 and the 705 were the first commercial machines with core memories.
	IBM 705 announced. Developed primarily to handle business data, it could multiply numbers as large as one billion at a rate of over 400 per second. In a 1954 IBM publication, the 705 was credited with "Forty thousand or twenty thousand characters of high-speed magnetic core storage; Any one of the characters in magnetic core storage can be located or transferred in 17 millionths of a second; Any one of these characters is individually addressable."
	Honeywell computer business was originated from the Datamatic Corporation, founded in Newton MA, as a joint-venture by Raytheon and Honeywell, to produce large-scale computer systems. Raytheon sells its 40% interest to Honeywell in 1957

	The 2nd Generation Transistor Computer Systems
1956	The Air Force accepts the first UNIVAC Solid State Computer. The machine was one of the first to use solid state components in its central processing unit. Remington Rand was not able to market a commercial version for three years. The UNIVAC Solid State Computer came in two versions: the Solid State 80 handled IBM-style 80 column cards, while the Solid State 90 was adapted for Remington Rand's 90 column cards. A Solid State system consisted of the CPU and drum memory, card reader, card punch, and printer. There was the option of adding a tape controller and up to ten UNISERVO II tape drives. The drives could read both mylar tape and the old UNIVAC metallic tape: the mode was selected by a switch on the front of the drive. Actually a hybrid, the CPU had twenty vacuum tubes, 700 transistors, and 3000 FERRACTOR amplifiers.
1957	Installation of the first Honeywell Datamatic D-1000 to Blue Cross/Blue Shield of Michigan.
1958	Introduction of Honeywell H-800 first shipped in 1960.
	Delivery of first GE ERMA system. Two years later it is renamed GE-210. It was also sold by NCR as NCR-204.
1959	The fully transistorized IBM 7090 computer system delivered. The system had computing speeds up to five times faster than those of its predecessor, the IBM 709. It was both a scientific and business machine. It was finally withdrawn from production in 1969
	The IBM 1401 was called the Model T of the computer business, because it was the first mass-produced digital, all-transistorized, business computer that could be afforded by many businesses worldwide. The basic 1401 was about 5 feet high and 3 feet across. It came with 4,096 characters of memory. The memory was 6-bit (plus 1 parity bit) CORE memory, made out of little metal donuts strung on a wire mesh at IBM factories. The 1401 had an optional Storage Expansion Unit which expanded the core storage to an amazing 16K. The 1401 processing unit could perform 193,300 additions of eight-digit numbers in one minute. The monthly rental for a 1401 was $2,500 and up, depending on the configuration. By the end of 1961, the number of 1401s installed in the United States alone had reached 2,000 -- representing about one out every four electronic stored-program computers installed by all manufacturers at that time. The number of installed 1401s peaked at more than 10,000 in the mid-1960s, and the system was withdrawn from marketing in February 1971.
1960	UNIVAC announced the 1107( actually completed in 1962) with the EXEC I operating system which occupied about 8K of the 1107's 32K of memory. It was intended to support true multiprogramming: sharing CPU time among several batch runs.
	Introduction of Honeywell 400
	Decision to launch the GE Mosaic line, a family of four 24-bits computers. The lower models will be announced as GE-415, GE-425 and GE-435. They will be known as Compatible GE-400 series.
1961	IBM 7040 and 7044 computer systems announced.
1962	Introduction of Honeywell 1800 (first shipped in 1964).
	IBM's 1440 Data Processing System was a low-cost compact electronic computer designed specifically for small and medium-size business firms.
	IBM 7094 computer announced. With a memory reference speed of two microseconds (millionth of a second), the 7094 could in one second perform 500,000 logical decisions, 250,000 additions or subtractions, 100,000 multiplications or 62,500 divisions. The 7094 internally performed mathematical computations 1.4 to 2.4 times faster than the IBM 7090, A typical 7094 sold for $3,134,500. IBM provided customers with a complete package of 7090/7094 programs, including FORTRAN and COBOL programming languages, input-output control system and sorting, without charge. The 7094 was withdrawn from marketing in 1969.
1963	Introduction of Honeywell H-200, a machine targeting the IBM 1401, with a similar architecture and a "Liberator" program translator.

	The 3rd Generation computers Multiprocessing and operating systems make the scene
1960's	Burroughs B5000 mainframe introduced. The system can be considered the first of the "third generation" of computer systems. The most remarked-upon aspects are its use of a hardware-managed stack for calculation, and the extensive use of descriptors for data access. It included virtual memory -- perhaps the first commercial computer to do so -- as well as support for multiprogramming and multiprocessing.
1964	CDC (Computer Data Corp.) 6600 shipped; 100 nsec cycle time.
	First GE Time-sharing operation at Dartmouth College of the DTSS Dartmouth time-sharing system on a GE-265 (GE-225 + Datanet-30)
	IBM announces the 360 family of computer systems.
	The Burroughs B5500, appeared. It also had multiprogramming and virtual memory capabilities, but was three times faster than the B5000
1965	IBM ships the midrange 360 model 40 computer which had COBOL and FORTRAN programming languages available as well as the stock Basic Assembly Language (BAL) assembler.
	Introduction of GECOS-II, a multi-programming operating system for the GE-600
1966	The Burroughs B6500, which was actually an improved version of the B5500.
1967	First IBM 360/Model 91 shipped to NASA GSFC.
1969	First shipment of the CDC 7600 computer system.
	First shipment of IBM 360 Model 85. The 360 family was intended to have 3 operating systems: DOS/360 operating system for the small machines. It could run two "real-time" sessions and one batch session. OS/360 operating system for the midrange and high end. TSS/360 operating system for Time-sharing Multi-user system
	Introduction of Honeywell model 115 in the H-200 product line. The line was renamed H-2000 after models 115/2, 1015 and 2015 introduced in January 1971, and model 2020 and 2030 in December 1972 after the GE merger. The line was eventually merged into Series6 0 NPL through a H-200 mode (emulator) on level 64.
	Introduction of GE-655 that was better known as H-6000 after 1970.
1970	Burroughs announces the 700 series. The first B6700 computer systems were installed during 1971. It was the first Burroughs machine with dynamic linking of programs at runtime. The B6700 line started out with one CPU and one i/o processor and could be expanded up to a maximum of three CPUs and two i/o processors.
	Formal acquisition of Bull-General Electric by Honeywell. BGE takes the name of Honeywell-Bull.
	IBM announces a family of machines with an enhanced instruction set, called System/370. The 370s proved so popular that there was a two-year waiting list of customers who had ordered a systems.
	A giant dies: Announcement of the cession of the world-wide GE computer business, except time-sharing to Honeywell.
1971	US Air Force orders several Honeywell H-6000 WWMCCS (World Wide Military Command and Control System), a $3.5M contract.
	First shipments of IBM S/370 Models 155 and 165 as well as the S/360 Model 195.
1973	Introduction of virtual memory on IBM S/370 Models 158 and 168.
1975	Amdahl 470 V/6 computer system delivered to NASA.
1977	The Burroughs Scientific Processor was developed, and announced.
	IBM 3033 computer system announced
1979	The Burroughs 900-level systems were introduced.
1985	The most powerful IBM computer system of its time, the 3090 high-end processor of the IBM 308X computer series incorporated one-million-bit memory chips, Thermal Conduction Modules to provide the shortest average chip-to-chip communication time of any large general purpose computer. The Model 200 (entry-level with two central processors) and Model 400 (with four central processors) IBM 3090 had 64 and 128 megabytes of central storage, respectively. At the time of announcement, the purchase price of a Model 200 was $5 million. A later six-processor IBM 3090 Model 600E, using vector processors, could perform computations up to 14 times faster than the earlier four-processor IBM 3084.
1990	The ES/9000 models came out with fiber-optical I/O channels (ESCON), and IBM began using the name System/390. The ES/9000s exploited new technologies, such as high-speed fiber optic channels with IBM's new ESCON architecture, ultra-dense circuits and circuit packaging that provided higher performance, extended supercomputing capabilities and twice the processor memory previously available. The line spanned a 100-fold performance range increase from the smallest (model 120) to the most powerful (model 900 six-way multiprocessor). Basic purchase prices for the air-cooled processors of ES/9000 ranged from approximately $70,500 to $3.12 million. Basic purchase prices for the water-cooled models ranged from $2.45 million to $22.8 million.
1999	IBM releases a new generation of S/390.
2002	The S/390 G5/G6 enterprise server family has up to 256 channels, from 2 to 8 Cryptographic Coprocessors, from 8 to 32 Gigabytes of memory, and can run under OS/390, MVS, VM, VSE, or TPF operating systems. It can also host an unbelievable amount of hard drive storage. Let's see a PC match that!
2004	The 3/4 ton IBM eServer zSeries 890, dubbed the "Baby Shark" can host up to 32 GBytes of memory. The four PCIX Crypto Coprocessor (and optional PCI Crypto Accelerators) on the z890 have seven engine levels, giving a total of 28 capacity settings overall. With it's advanced virtualization technology the 64-bit z890 can run several operating systems at the same time including z/OS, OS/390®, z/VM®, VM/ESA®, VSE/ESA, TPF and Linux for zSeries and Linux for S/390®. The z890 is upgradeable within z890 family and can also upgrade to z990 from select z890 configurations. Configured with the new Enterprise Storage Server Model 750 which handles from 1.1TB up to 4.6TB of data, the x890 makes an awesome server.
2007	IBM produces the Blue-Gene/P, a system capable of a petaflop (1,000,000 gigaflops or 1,000 teraflops). It sports 73,728 processors comprised of four cores each of IBM’s 850MHz PowerPC 450, resulting in 294,912 cores. The system can be scaled to nearly three times that size, resulting in a 3 petaflop capability and is all hooked up via a high-end optical network.

Sources

A Short History of the Second American Revolution
by Dilys Winegrad and Atsushi Akera
Dr. Dobb's History of Computing
IBM
IBM 360/370/3090/390
by Lars Poulsen
Manhattan Project History
Society for the Historical Preservation of the Manhattan Project
Unisys History Newsletter

BULL computers chronological history
ENIAC Story, The
by Martin H. Weik
IBM Advanced Computing Systems -- Draft Timeline
by Mark Smotherman
Incredible Shrinking Computer, The
by Matt Lake
Technological Threshold, The
Visit the Computer History Museum
by Barbara Darrow, Larry Hooper & Kristen Kenedy

What is Parallel Sysplex ?

2010-01-05T17:09:00.005+05:30

The above diagram illustrates schematic representation of Parallel Sysplex

In IBM mainframe computers, a Systems Complex, commonly called a Sysplex, allows multiple processors to be joined into a single unit, sharing the same Sysplex name and Couple Data Sets. Put another way, a Sysplex is a single logical system running on one or more physical systems. Sysplexes are often isolated within a single system, but Parallel Sysplex technology allows multiple mainframes to act as one.

Components of a Sysplex include:

A Sysplex Timer which synchronizes all member systems' clocks;
Global Resource Serialization (GRS), which allows multiple systems to access the same resources concurrently, serializing where necessary to ensure exclusive access;
Cross System Coupling Facility (XCF), which allows systems to communicate peer to peer;
Couple Data Sets (CDS);

In computing, a Parallel Sysplex is a cluster of IBM mainframes acting together as a single system image with z/OS. Used for disaster recovery, Parallel Sysplex combines data sharing and parallel computing to allow a cluster of up to 32 systems to share a workload for high performance and high availability.

Major components of a Parallel Sysplex include:

Coupling Facility (CF or ICF) hardware, allowing multiple processors to share, cache, update, and balance data access;
Sysplex Timers or Server Time Protocol to synchronize the clocks of all member systems
High speed, high quality, redundant cabling;
Software (operating system services and, usually, middleware such as DB2).

The Coupling Facility may be either a dedicated external system (a small mainframe, such as a System z9 BC, specially configured with only coupling facility processors) or integral processors on the mainframes themselves configured as ICFs (Internal Coupling Facilities). It is recommended that at least one external CF be used in a parallel sysplex. A Parallel Sysplex has at least two CFs and/or ICFs for redundancy. Every mainframe participating in a Parallel Sysplex does not need an ICF or its own external CF — mainframes merely attach, via cables, to the external CFs or ICFs.

A Sysplex Timer is a physically separate piece of hardware from the mainframe, whereas STP is an integral facility within the mainframe's microcode.

With STP and ICFs it is possible to construct a complete Parallel Sysplex installation with two connected mainframes. Moreover, a single mainframe can contain the internal equivalent of a complete physical Parallel Sysplex, useful for application testing and development purposes.

What is Batch Processing ?

2009-12-25T11:03:00.003+05:30

Batch processing is execution of a series of programs ("jobs") on a computer without manual intervention.

Batch jobs are set up so they can be run to completion without manual intervention, so all input data is preselected through scripts orcommand-line parameters. This is in contrast to "online" or interactive programs which prompt the user for such input. A program takes a set of data files as input, process the data, and produces a set of output data files. This operating environment is termed as "batch processing" because the input data are collected into batches on files and are processed in batches by the program.

Benefits of Batch Processing:

It allows sharing of computer resources among many users and programs
It shifts the time of job processing to when the computing resources are less busy
It avoids idling the computing resources with minute-by-minute manual intervention and supervision
By keeping high overall rate of utilization, it better amortizes the cost of a computer, especially an expensive one.

Common Batch Processing Usage:

Data processing:
A typical batch processing procedure is End of day-reporting (EOD), especially on mainframes. Historically systems were designed to have a batch window where online subsystems were turned off and system capacity was used to run jobs common to all data (accounts, users or customers) on a system. In a bank, for example, EOD jobs include interest calculation, generation of reports and data sets to other systems, print (statements) and payment processing.
Printing:
A popular computerized batch processing procedure is printing. This normally involves the operator selecting the documents they need printed and indicating to the batch printing software when, where they should be output and priority of the print job. Then the job is sent to the print queue from where printing daemon sends them to the printer.

Databases:
Batch processing is also used for efficient bulk database updates and automated transaction processing, as contrasted to interactive online transaction processing (OLTP) applications.

Images:
Batch processing is often used to perform various operations with digital images. There exist computer programs that let one resize, convert, watermark, or otherwise edit image files.

Converting:
Batch processing is also used for converting a number of computer files from one format to another. This is to make files portable and versatile especially for proprietary and legacy files where viewers are not easy to come by.

Difference between Supercomputers and Mainframes

2009-12-25T10:34:00.003+05:30

Supercomputers are very different from mainframe computers. A supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation. Supercomputer can be based on any type of computer design (e.g., FPGA, vector processing,microprocessor, and GPGPU based computer).Supercomputers are used for scientific and engineering problems which are limited by processing speed and memory size, while mainframes are used for problems which are limited by input/output and reliability and for handling multiple business transactions concurrently. The differences are as follows:

Mainframes are measured in integer operations per second or MIPS; whereas, Supercomputers are measured in floating point operations per second or FLOPS. Example of integer operation is moving data around in memory or adding integers. Example of floating point operation is the calculation of mathematical equations in real numbers. In terms of computational ability, Supercomputers are more powerful. Mainframes are built to be reliable for transaction processing as it is commonly understood in the business world: a commercial exchange of goods, services, or money. A typical transaction would include the updating to a database system for such things as inventory control (goods), airline reservations (services), or banking (money). A transaction could refer to a set of operations including disk read/writes, operating system calls, or some form of data transfer from one subsystem to another.
Both types of systems offer parallel processing, although this has not always been the case. Parallel processing (i.e., multiple CPUs executing instructions simultaneously) was used in supercomputers (e.g., the Cray-1) for decades before this feature appeared in mainframes. Supercomputers typically expose parallel processing to the programmer in complex manners, while mainframes typically use it to run multiple tasks. One result of this difference is that adding processors to a mainframe often speeds up the entire workload transparently, with important exceptions of single batch jobs and CICS regions that don't run faster.
Supercomputers are often built to run complex algorithm in wide application area such as in industry, academic, research, government or military (e.g., nuclear simulation and modeling, life science, medicine, telecommunication, weather forecasting), while mainframes run simple algorithm to handle variety of tasks (e.g. database query, warehousing, inventory, operating system). Supercomputer uses both off-design technology (e.g.: microprocessor based cluster computer) or advanced technology (e.g., vector processing, NUMA, liquid-cooling); whereas mainframes typically form part of a manufacturer's standard model lineup.
Mainframes tend to have numerous ancillary service processors assisting their main central processors (for cryptographic support, I/O handling, monitoring, memory handling, etc.) so that the actual "processor count" is much higher than would otherwise be obvious. Supercomputer design tends not to include as many service processors since they don't appreciably add to raw number-crunching power.
Mainframes are exceptionally adept at batch processing, such as billing, owing to their heritage, decades of increasing customer expectations for batch improvements. Supercomputers are very expensive and not cost-effective just to perform batch or transaction processing.

General History of Mainframes

2009-12-24T10:29:00.003+05:30

Several manufacturers produced mainframe computers from the late 1950s through the 1970s. The group of manufacturers was first known as "IBM and the Seven Dwarfs": IBM, Burroughs, UNIVAC, NCR, Control Data, Honeywell, General Electric and RCA. Later, shrinking, it was referred to as IBM and the BUNCH. IBM's dominance grew out of their 700/7000 series and, later, the development of the 360 series mainframes.

Notable manufacturers outside the USA were Siemens and Telefunken in Germany, ICL in the United Kingdom, and Fujitsu,Hitachi, Oki, and NEC in Japan. The Soviet Union and Warsaw Pact countries manufactured close copies of IBM mainframes during the Cold War; the Strela is an example of an independently designed Soviet computer.

Shrinking demand and tough competition caused a shakeout in the market in the early 1980s — RCA sold out to UNIVAC and GE also left; Honeywell was bought out by Bull; UNIVAC became a division of Sperry, which later merged with Burroughs to form Unisys Corporation in 1986. In 1991, AT&T briefly owned NCR. During the same period, companies found that servers based on microcomputer designs could be deployed at a fraction of the acquisition price and offer local users much greater control over their own systems given the IT policies and practices at that time. Terminals used for interacting with mainframe systems were gradually replaced by personal computers. Consequently, demand plummeted and new mainframe installations were restricted mainly to financial services and government. In the early 1990s, there was a rough consensus among industry analysts that the mainframe was a dying market as mainframe platforms were increasingly replaced by personal computer networks. Infoworld's Stuart Alsop famously predicted that the last mainframe would be unplugged in 1996.

That trend started to turn around in the late 1990s as corporations found new uses for their existing mainframes and as the price of data networking collapsed in most parts of the world, encouraging trends toward more centralized computing. The growth of e-business also dramatically increased the number of back-end transactions processed by mainframe software as well as the size and throughput of databases. Batch processing, such as billing, became even more important (and larger) with the growth of e-business, and mainframes are particularly adept at large scale batch computing. Another factor currently increasing mainframe use is the development of the Linux operating system, which arrived on IBM mainframe systems in 1999 and is typically run in scores or hundreds virtual machines on a single mainframe. Linux allows users to take advantage of open source software combined with mainframe hardware RAS. Rapid expansion and development in emerging markets, particularly China, is also spurring major mainframe investments to solve exceptionally difficult computing problems, e.g. providing unified, extremely high volume online transaction processing databases for 1 billion consumers across multiple industries (banking, insurance, credit reporting, government services, etc.) In late 2000 IBM introduced 64-bit z/Architecture, acquired numerous software companies such as Cognos and introduced those software products to the mainframe.

Characteristics of Mainframes

2009-12-23T09:45:00.002+05:30

Nearly all mainframes have the ability to run (or host) multiple operating systems, and thereby operate not as a single computer but as a number of virtual machines. In this role, a single mainframe can replace dozens or even hundreds of smaller servers. While mainframes pioneered this capability, virtualization is now available on most families of computer systems, though not always to the same degree or level of sophistication.

Mainframes can add or hot swap system capacity non disruptively and granularly, to a level of sophistication usually not found on most servers. Modern mainframes, notably the IBM zSeries, System z9 and System z10 servers, offer two levels of virtualization: logical partitions (LPARs, via the PR/SM facility) and virtual machines (via the z/VM operating system). Some IBM mainframe customers run no more than two machines : one in their primary data center, and one in their backup data center—fully active, partially active, or on standby—in case there is a catastrophe affecting the first building. Test, development, training, and production workload for applications and databases can run on a single machine, except for extremely large demands where the capacity of one machine might be limiting. Such a two-mainframe installation can support continuous business service, avoiding both planned and unplanned outages. In practice most customers use multiple mainframes linked by Parallel Sysplex and shared DASD.

Mainframes are designed to handle very high volume input and output (I/O) and emphasize throughput computing. Since the mid-1960s, mainframe designs have included several subsidiary computers (called channels or peripheral processors) which manage the I/O devices, leaving the CPU free to deal only with high-speed memory. It is common in mainframe shops to deal with massive databases and files. Giga-record or tera-record files are not unusual.Compared to a typical PC, mainframes commonly have hundreds to thousands of times as muchdata storage online, and can access it much faster.Other server families also offload I/O processing and emphasize throughput computing.

Mainframe return on investment (ROI), like any other computing platform, is dependent on its ability to scale, support mixed workloads, reduce labor costs, deliver uninterrupted service for critical business applications, and several other risk-adjusted cost factors.

Mainframes also have execution integrity characteristics for fault tolerant computing. For example, z900, z990, System z9, and System z10 servers effectively execute result-oriented instructions twice, compare results, arbitrate between any differences (through instruction retry and failure isolation), then shift workloads "in flight" to functioning processors, including spares, without any impact to operating systems, applications, or users. This hardware-level feature, also found in HP's NonStop systems, is known as lock-stepping, because both processors take their "steps" (i.e. instructions) together. Not all applications absolutely need the assured integrity that these systems provide, but many do, such as financial transaction processing.

Description of Mainframe computers

2009-12-21T07:47:00.003+05:30

Modern mainframe computers have abilities not so much defined by their single task computational speed (usually defined as MIPS — Millions of Instructions Per Second) as by their redundant internal engineering and resulting high reliability and security, extensive input-output facilities, strict backward compatibility with older software, and high utilization rates to support massive throughput. These machines often run for years without interruption, with repairs and hardware upgrades taking place during normal operation.

Software upgrades are only non-disruptive when Parallel Sysplex is in place, with true workload sharing, so one system can take over another's application, while it is being refreshed. More recently, there are several IBM mainframe installations that have delivered over a decade of continuous business service as of 2007, with hardware upgrades not interrupting service. Mainframes are defined by high availability, one of the main reasons for their longevity, because they are typically used in applications where downtime would be costly or catastrophic. The term Reliability, Availability and Serviceability (RAS) is a defining characteristic of mainframe computers. Proper planning (and implementation) is required to exploit these features.

In the 1960s, most mainframes had no interactive interface. They accepted sets of punch cards, paper tape, and/or magnetic tape and operated solely in batch mode to support back office functions, such as customer billing. Teletype devices were also common, at least for system operators. By the early 1970s, many mainframes acquired interactive user interfaces and operated as timesharing computers, supporting hundreds or thousands of users simultaneously along with batch processing. Users gained access through specialized terminals or, later, frompersonal computers equipped with terminal emulation software. Many mainframes supported graphical terminals (and terminal emulation) by the 1980s (if not earlier). Nowadays most mainframes have partially or entirely phased out classic terminal access for end-users in favor of Web user interfaces. Developers and operational staff typically continue to use terminals or terminal emulators.

Historically, mainframes acquired their name in part because of their substantial size, and because of requirements for specialized heating, ventilation, and air conditioning (HVAC), and electrical power. Those requirements ended by the mid-1990s with CMOS mainframe designs replacing the older bipolar technology. In a major reversal, IBM now touts its newer mainframes' ability to reduce data center energy costs for power and cooling, and the reduced physical space requirements compared to server farms.

Mainframe computer

2009-12-20T19:04:00.000+05:30

Mainframes (often colloquially referred to as Big Iron) are computers used mainly by large organizations for critical applications, typically bulk data processing such ascensus, industry and consumer statistics, enterprise resource planning, and financial transaction processing.

The term originally referred to the large cabinets that housed the central processing unit and main memory of early computers. Later the term was used to distinguish high-end commercial machines from less powerful units.

In 2009, the term refers to computers compatible with the IBM System/360line, first introduced in 1965. (IBM System z10 is the latest incarnation.) Otherwise, large systems that are not based on the System/360 but are used for similar tasks are usually referred to as servers. However, "server" and "mainframe" are not synonymous (see client-server).

Some non-System/360-compatible systems derived from or compatible with older (pre-Web) server technology may also be considered mainframes. These include the Burroughs large systems, the UNIVAC 1100/2200 series systems, and the pre-System/360 IBM 700/7000 series. Most large-scale computer system architectures were firmly established in the 1960s and most large computers were based on architecture established during that era up until the advent of Web servers in the 1990s. (Interestingly, the first Web server running anywhere outside Switzerland ran on an IBM mainframe at Stanford University as early as 1990. See History of the World Wide Web for details.)

There were several minicomputer operating systems and architectures that arose in the 1970s and 1980s, but minicomputers are generally not considered mainframes. (UNIX arose as a minicomputer operating system; Unix has scaled up over the years to acquire some mainframe characteristics.)

Many defining characteristics of "mainframe" were established in the 1960s, but those characteristics continue to expand and evolve to the present day.

HI

2009-12-20T18:57:00.000+05:30

Welcome to this Blog..

I'll post periodically about Mainframes & it's programming..

It's All About Mainframes..!

What is ERP ?

This is were we are heading...!

JCL Interview Questions

Why Mainframe cannot be Hacked ?

Role of Production Control Analyst

Role of System Operator

Role of Application Programmer

Role of System Administrator

Role of the System Programmer

History of Mainframe Computer

The 1st Generation
The tube-based mainframe computers

The 2nd Generation
Transistor Computer Systems

The 3rd Generation computers
Multiprocessing and operating systems make the scene

Sources

What is Parallel Sysplex ?

What is Batch Processing ?

Data processing:

Printing:

Databases:

Images:

Converting:

Difference between Supercomputers and Mainframes

General History of Mainframes

Characteristics of Mainframes

Description of Mainframe computers

Mainframe computer

HI

It's All About Mainframes..!

What is ERP ?

This is were we are heading...!

JCL Interview Questions

Why Mainframe cannot be Hacked ?

Role of Production Control Analyst

Role of System Operator

Role of Application Programmer

Role of System Administrator

Role of the System Programmer

History of Mainframe Computer

The 1st GenerationThe tube-based mainframe computers

The 2nd GenerationTransistor Computer Systems

The 3rd Generation computersMultiprocessing and operating systems make the scene

Sources

What is Parallel Sysplex ?

What is Batch Processing ?

Data processing:

Printing:

Databases:

Images:

Converting:

Difference between Supercomputers and Mainframes

General History of Mainframes

Characteristics of Mainframes

Description of Mainframe computers

Mainframe computer

HI

The 1st Generation
The tube-based mainframe computers

The 2nd Generation
Transistor Computer Systems

The 3rd Generation computers
Multiprocessing and operating systems make the scene