TechTinkering

Programmable Character Sets: A Simple Alternative to Bitmap Displays

29 May 2013 00:00:01 BST

Programmable or reconfigurable character sets were a simple alternative to fully bitmappable displays. The main driving force behind their creation was a desire to keep the cost of computers low: RAM was expensive and bitmappable displays need more complex hardware. Programmable character sets we...

Adding a Basic Stub to a Vic-20 Assembly Language Program

10 May 2013 00:00:01 BST

To make machine language programs more friendly it is nice to add a basic stub which contains a line with a SYS statement to start the code. This is easy to do on the Vic-20 and the process gives you an insight into how Basic programs are stored in memory. I’ll show you how to do this and h...

Creating a TTY Simulator in Assembly Language on the Vic-20

04 May 2013 00:00:01 BST

The Vicmon machine language cartridge is an excellent tool for exploring the Vic-20. This article and its associated video will show you how to use it to create a simple program that will change the normal output of a Vic so that it feels a bit like a teletype terminal. This will be done by takin...

BBS Ads: Getting the Word Out

23 Apr 2013 00:00:01 BST

BBS Ads were important to users and sysops of BBS’s. There wasn’t any universal directory like the phone book, and during the heyday of BBS’s (early ’80s to the mid ’90s), most people couldn’t easily access the Internet. Every BBS had a different atmosphere. It...

Beginning Assembly Programming on the Commodore Vic-20

16 Apr 2013 00:00:01 BST

The Commodore Vic-20 is a great machine to learn an assembly language on. It was released in 1981 and was the first computer to sell one million units, which contributes to is popularity today. The machine is well documented, well supported through forums and much of the hardware is plentiful and...

Using C-Kermit to Exchange Files With Telnet BBS's

09 Apr 2013 00:00:01 BST

Most BBSs that are still running now do so via telnet. In many ways this is great as it allows people from all around the world to access a BBS as if it were local to them. The problem comes though, when you want to upload or download a file to/from the BBS. Most telnet clients don’t make t...

Connecting to a Remote Serial Port over TCP/IP

02 Apr 2013 00:00:01 BST

Most modern machines don’t have a serial port as standard; you could use a USB to serial lead, however, if you have another machine available that does have a serial port you can access it remotely over TCP/IP. Using ser2net to Connect a Serial Port to a TCP port ser2net listens to a TCP ...

Using Netcat to Create ad hoc Links Between Applications or Machines

25 Mar 2013 00:00:01 GMT

Netcat is a simple Unix utility which reads and writes data across network connections using the TCP or UDP protocol. It is often described as the “Swiss-army knife for TCP/IP” because of its flexibility and is often used to debug and investigate network connections directly from the ...

If Only Borland Had Stuck With Turbo Modula-2 For CP/M

12 Mar 2013 00:00:01 GMT

I have written previously about why Turbo Pascal is a Great Choice For Programming Under CP/M and now it is time to talk about what could have been. You probably haven’t heard of Turbo Modula-2 for CP/M as it was only on the market for a brief period of time. However, it was a superb produc...

Turbo Pascal: A Great Choice For Programming Under CP/M

05 Mar 2013 00:00:01 GMT

CP/M was blessed with many programming languages, each with their own strengths and weaknesses. I think that Turbo Pascal stands out from these and I’m not alone. When Turbo Pascal was released in 1983 by Borland, as their first software development application, it was quickly adopted by sc...

xdgbasedir: A Tcl Module to Access the XDG Base Directory Specification

27 Feb 2013 00:00:01 GMT

Unix has traditionally lacked a consistent way of storing user specific and system wide configuration and support files. This has lead to a mess of dot files in a user’s home directory and other associated files being all over the file system. The XDG Base Directory Specification describes ...

Compiling a Tcl Script into an Executable

20 Feb 2013 00:00:01 GMT

Locating Tcl scripts to load from an executable can be awkward if you want to make your program cross-platform. An easier way is to compile a Tcl script directly into the executable and let that script find any other scripts needed. This is particularly relevent as so many programs just use a sin...

Floppy Days: A New Vintage Computing Podcast

19 Feb 2013 00:00:01 GMT

I have just finished listening to the first episode of Floppy Days and I’m pleased to report that it looks like this is going to be a good addition to the vintage computing landscape. The presenter, Randy Kindig, admits that he has been quite quiet within the retro community. However, he se...

Using Dynamically Generated Header Files with CMake

12 Feb 2013 00:00:01 GMT

Sometimes it can be useful to dynamically generate header files and include them from a C source file. However, it can be a little difficult getting CMake to recognize when to generate the files and when to recompile the source files that include those headers. What follows is a method to do this...

Embedding an SDL Surface in a Tk Window

26 Jun 2012 00:00:01 BST

Tk is great, but sometimes it just isn’t fast enough. SDL is fast, but has no support for input dialogs and other GUI conventions. By embedding an SDL surface in a Tk window you get the best of both worlds. Whether you want to use Tk to add a nice GUI to an SDL app or want to access SDL via...

Refactoring: Arm Yourself in the War Against Useless Comments

26 Apr 2012 00:00:01 BST

Comments, comments, everywhere, but are they making your code clearer or just distracting you? Comments are meant to be there to explain code and help you to understand it. However, they are often out of step and therefore can confuse. Think seriously before adding comments; it is often better to...

Dealing Sympathetically with Legacy Code

20 Apr 2012 00:00:01 BST

I have often noticed programmers getting worked up about the legacy code they are maintaining. I know it is annoying having to wade through poor code, or worrying about making changes for fear of unexpected side-effects. However, it is important to see the code for what it is and in the context o...

Pisceans and October Babies More Likely to Become Poets. Scraping Wikipedia Reveals All

08 Sep 2011 00:00:01 BST

This is the second in a series of articles looking into whether when you were born affects your future. In the previous article I looked at Nobel laureates, which are, of course, from a range of fields. Now it is time to focus on just one discipline with poets. I have again used ScraperWiki to sc...

Does When You Were Born Affect Your Chance of Becoming a Nobel Laureate? Scraping Wikipedia to Find Out

24 Aug 2011 00:00:01 BST

There has been a lot of talk in the UK recently about whether when you were born affects your schooling. Lots of teachers have noticed how pupils born at the end of the Summer often struggle compared with those born in the Autumn, which makes sense because the latter group are almost a year older...

Improving the related_posts feature of jekyll

17 Aug 2011 00:00:01 BST

Now that I have converted TechTinkering over to Jekyll, I have come up against a bit of a problem with site.related_posts: The results are always just the latest posts, and are not filtered or ordered for relevance. I see that lots of people are struggling with a similar problem and have therefor...

Mida - A Microdata parser/extractor library for Ruby

16 Apr 2011 00:00:01 BST

I have recently released Mida as a Gem for parsing/extracting Microdata from web pages. Not many sites at the moment are using Microdata, in fact, apart from this site, I only know of one other: Trust a Friend, which is another site that I work on. However, as HTML5 is more widely adopted I am su...

A Jekyll Plugin to Display Ratings as Star Images

15 Feb 2011 00:00:01 GMT

I have been using Jekyll a lot recently on the Trust a Friend website and found the need to display a rating as a series of stars. Initially I implemented this in JavaScript, which worked fine, but I like to limit the amount of JavaScript on my sites. I could have done this with some straight Liq...

The National Museum of Computing at Bletchley Park

15 Jun 2010 00:00:01 BST

The National Museum of Computing is the UK’s largest museum dedicated to computing. It is located on the Bletchley Park estate just south of Milton Keynes and is easy to get to by car, bus or train. Tickets are £10 for an Adult, with a discount for booking on-line. They allow you access to ...

xAce is Back in Active Development and Looking For Contributors

06 May 2010 00:00:01 BST

xAce is a great Jupiter Ace emulator and is in fact the one that I use the most, however it hasn’t been actively developed since 1997 and therefore has some shortcomings. I am keen to improve the emulator and have quite a few plans for it. I have been in touch with Edward Patel, the origina...

Introducing TextPix v0.1 - A program to convert an image into a character set and text mode screen data

16 Apr 2010 00:00:01 BST

I have today released TextPix v0.1 This is a program to take an image and convert it into a redefined character set and the associated text mode screen data referencing that character set. The program came about because I wanted to be able to load images on the Jupiter Ace, but the Ace has no wa...

Getting Colour ANSI Emulation to Work Properly When Connecting to a BBS With Telnet Under Linux

14 Feb 2010 00:00:01 GMT

I have noticed that the number of people interested in using telnet to access BBSs seems to be growing, which I’m really pleased to see. However lots of people seem to be having trouble getting colour ANSI emulation working properly with telnet under Linux. I have therefore put this tutoria...

Setting up a Beowulf Cluster Using Open MPI on Linux

02 Dec 2009 00:00:01 GMT

I have been doing a lot of work recently on Linear Genetic Programming. This requires a great deal of processing power and to meet this I have been using Open MPI to create a Linux cluster. What follows is a quick guide to getting a cluster running. The basics really are very simple and, dependin...

My Top 10 Classic Text Mode BSD Games

11 Aug 2009 00:00:01 BST

Recently, I have been playing a collection of text mode games that were commonly found on Unix Systems during the 70s and 80s. These games are surprisingly playable and, for me, they really show that there is more to gaming than flashy graphics. As with any top 10 list, everyone will have their o...

Running 4K FORTRAN on a DEC PDP-8

14 Jul 2009 00:00:01 BST

4K FORTRAN was a subset of FORTRAN II and was the first high-level language available for the DEC PDP-8. It consisted of two parts: the 4K FORTRAN Compiler (nicknamed “Fivetran”) and the 4K FORTRAN Operating System. The compiler was written by Larry Portner and the operating system wa...

A Quickstart Guide to Editing Paper Tape With the Symbolic Tape Editor on the DEC PDP-8

16 Jun 2009 00:00:01 BST

Before re-writable storage devices, such as tape drives, become popular for the DEC PDP-8, owners had to rely on paper tape. This was fine for loading programs on pre-punched tape, but left the problem of how to put new data onto punched tape and how to edit existing data. This could be done off-...

Book Review: Electronic Brains: Stories from the Dawn of the Computer Age by Mike Hally

03 Jun 2009 00:00:01 BST

This is an interesting history of computer development around the world during the 1940s and 50s. The book grew out of a radio series on BBS Radio 4 and contains lots of original material gained from interviews in 2001 and 2004. It is very accessible as it focuses slightly more on the...

Emulating a DEC PDP-8 with SimH

26 May 2009 00:00:01 BST

The DEC PDP-8 mini-computer was launched on 22 March 1965 and was a great success. It was fairly cheap for the day and could easily be expanded. What attracts me most to the PDP-8 is its simple design. I therefore decided to experiment with the SimH emulation of this machine, but found that the d...

Improving the Standard SUBLEQ OISC (One Instruction Set Computer) Architecture

15 May 2009 00:00:01 BST

When I first came across The SUBLEQ URISC (Ultimate RISC) / OISC (One Instruction Set Computer) Architecture, I really liked the beauty and simplicity of the design. However, I have now been experimenting with it for quite a while and have noticed one aspect of the standard implementation that I ...

Connecting a Parallel Printer to a Modern Linux Machine Using a LogiLink USB to Parallel Cable, D-SUB 25pin

06 May 2009 00:00:01 BST

I have a number of older printers that I would like to connect to my modern machine, but have been unable to do so because my computer doesn’t have a parallel interface. After searching the internet for a review of a usb to parallel cable that works reliably with Linux, I pretty much drew a...

An Introduction to Corewar

30 Apr 2009 00:00:01 BST

I remember reading about Corewar roughly 20 years ago and thinking that I will have to have a go at that when I get the time. As often happens in life, things got in the way and I only recently managed to give it a go. I love the challenge of programming and the competitive aspect of this program...

The Smallest Communication Program in the World?

23 Apr 2009 00:00:01 BST

I was going through a backup of my dos machine, taken in 1998, and came across some source code which I haven’t seen for a long time. It was great to see that old code, and I must set-up a machine so that I can run some of it again. In particular I came across an attempt at writing the worl...

Hello, World! in SUBLEQ Assembly

29 Mar 2009 00:00:01 GMT

After writing a previous article: The SUBLEQ URISC (Ultimate RISC) / OISC (One Instruction Set Computer) Architecture. I was left thinking that I should really have given at least a “hello, world” program as a demonstration. I was then inspired after seeing John Metcalf’s post: ...

An Introduction to Test-Driven Development

18 Mar 2009 00:00:01 GMT

For the past 6 months I have been using Test-Driven Development (TDD) on a new project. It has made such a difference to the quality of my code, that I feel I just have to share it’s benefits with those who may not have heard of it. TDD reverses the normal order of testing as it requires de...

The SUBLEQ URISC (Ultimate RISC) / OISC (One Instruction Set Computer) Architecture

05 Mar 2009 00:00:01 GMT

I have been interested in the limits of RISC (Reduced Instruction Set Computer) architecture for a while and recently came across OISC (One Instruction Set Computer) \ URISC (Ultimate RISC) architecture when looking for a simple way to implement a Virtual Machine for an A.I. project I was working...

xAce - A Jupiter Ace Emulator for Unix (Patched to correct garbled display)

12 Feb 2009 00:00:01 GMT

The only Jupiter Ace emulator that I found, which would work under Linux, was written by Edward Patel and is called xace. There is also a Windows version available, but I don’t know anything more about that. The following instructions, taken partially from the site’s help instructions...

Book Review: The Mythical Man-Month: Essays on Software Engineering by Frederick P. Brooks, Jr.

26 Jan 2009 00:00:01 GMT

This book, written in 1975, offers a fascinating insight into the software engineering process used at that time. The author draws from his experience as project manager for the IBM System/360 and OS/360, and in doing so also sheds light on how they were put together. The 1995 edition, reviewed h...

Bouncing Babies

16 Dec 2008 00:00:01 GMT

Bouncing Babies is one of the first games I remember playing on an IBM PC Compatible. I recall looking at this funny game and thinking that it really was a strange concept. It was released as Shareware by Dave Baskin, but I believe that it is now Freeware. Here you can see the CGA graphics as th...

Chinese Man Spotted On Tissue

08 Dec 2008 00:00:01 GMT

It really is funny the things that we spot sometimes. Most of us must have looked up at the clouds and spotted animals, houses and other imagined objects. We are also used to the occasional news report of people finding images they recognise in the strangest of places, such as the girls who found...

My Top 10 Commodore 64 Demos

24 Nov 2008 00:00:01 GMT

There are so many great demos for the Commodore 64 and the demo scene is still thriving. Surprisingly there are even new effects being created for this machine. I have spent many hours going through a huge amount of demos to compile this list and I know that some of the entries are controversial,...

Beneath a Steel Sky, My Favourite Graphical Adventure Game

13 Nov 2008 00:00:01 GMT

Beneath a Steel Sky was released for the PC in 1994 by Revolution Software. It was received well and has gone on to be considered a cult classic. It uses the Virtual Theatre engine which was first used in Lure of the Temptress and among other things allows the non-player characters to have a basi...

How to File Good Bug Reports

12 Nov 2008 00:00:01 GMT

The real advantage of Open Source software is that many people from all around the globe can work to make it better. This means that bugs can be detected and often fixed much more quickly than with closed source software. The software does tend to be run on lots of platforms however, so there is ...

Using ScummVM to Play Classic Adventure Games

10 Nov 2008 00:00:01 GMT

ScummVM is Virtual Machine, that allows you to run adventure games created for a number of game creation engines. This is a great way of playing those classic adventure games that you loved so much, or never got a chance to play at the time. Some of them such as Beneath a Steel Sky have rarely be...

Writing my First Program to Toggle in to the IMSAI 8080

05 Nov 2008 00:00:01 GMT

I have long been fascinated with entering programs into computers by methods not involving a standard keyboard and monitor. This interest was peeked by my last article: Using the latest z80pack, version 1.17, to emulate an Altair 8800 or IMSAI 8080 using the new graphical FrontPanel. I have there...

Using the latest z80pack, version 1.17, to emulate an Altair 8800 or IMSAI 8080 using the new graphical FrontPanel

29 Oct 2008 00:00:01 GMT

Udo Munk has just released the latest version of his z80pack emulator, version 1.17, which now includes John Kichury’s FrontPanel library. As well as being a superb emulator to run CP/M on, it now gives you a great graphical representation of the Altair 8800 and IMSAI 8080 with fully functi...

Is this steamer really not to be used by girls?

28 Oct 2008 00:00:01 GMT

I was preparing the walls of our nursery on the weekend, ready for the arrival of our first child in December. I was about to start steaming off the border and thought I’d better look at the instructions on the steamer. The only writing on the steamer is the label pictured below and I could...

Using DOSBox to Run DOS Games and Applications

24 Oct 2008 00:00:01 BST

There were some brilliant games and applications released for DOS, and some of the games such as Command and Conquer are still very playable. There are a number of options to play these games today, from using a Virtual Machine such as QEMU, to DOSBox which is a dedicated DOS emulator. Both of th...

Installing the HI-TECH Z80 C Compiler for CP/M

22 Oct 2008 00:00:01 BST

My language of choice is C and I am currently getting more involved with the CP/M operating system. I have therefore decided that it would be nice to have a C compiler working under CP/M. There are a number of options available in the archives, but I have found that HI-TECH are allowing their CP/...

Installing ZDE 1.6, a programmers editor for CP/M

21 Oct 2008 00:00:01 BST

To do any serious programming under CP/M, the first thing you need is a good programmers editor. There aren’t many in the archives, but I have tried most of them and found ZDE to be the best. It is small, has lots of features, and uses Wordstar commands which are familiar to me and easy to ...

Setting up z80pack to Create an Emulated CP/M System

17 Oct 2008 00:00:01 BST

I have decided to try out some old CP/M software, but need something to run it on. I could either do this on my Commodore 128 or through emulation. Unfortunately the 1571 disk drive for my Commodore is currently out of action, so that leaves me with emulation. I was going to use...

PDP 8 in 'Three Days of the Condor'

14 Oct 2008 00:00:01 BST

I watched ‘Three Days of the Condor’ the other night and loved seeing what I believe is a Dec PDP 8/E being used. Also featured in connection with this machine was a DecWriter, paper tape reader and possibly a VT-52 video terminal. The film revolves around a CIA researcher, Robert Re...

Book Review: Fundamentals of Operating Systems by A.M. Lister - Second Edition

07 Oct 2008 00:00:01 BST

It was fascinating to read this book from 1979 and see how operating system design was viewed then, compared to now. The biggest change being the shift in importance from batch processing to the interactive use of computers. Despite the advances since this book was written, it is surprising how m...

How to share an SSL certificate and still use cookies

16 Sep 2008 00:00:01 BST

Website hosting companies often provide a shared SSL certificate, but this presents the web designer with the problem of how to use it for a site that uses cookies. I have read many people say that this can’t be done. However, this article will show a simple way of using a shared SSL certif...

Is COBOL really understandable after 14 years?

08 Aug 2008 00:00:01 BST

COBOL has been in the news quite a lot recently and I have been reading that there are still huge amounts of COBOL code running and being written. This led me to wonder why this language was still being used. I therefore decided to look at a few sites about COBOL and see what they said was good a...