Modula-2 is a great language in general and is a good choice for programming on CP/M. There are three good compilers available for CP/M which all require a Z80 processor and we'll compare each in turn| TechTinkering - Retro Computers, Programming, General Technical Tinkering
SUBLEQ is an interesting architecture because of its simplicity, adaptability and power. It is therefore an attractive choice for a simple virtual machine. However, this comes at a cost which we will| TechTinkering - Retro Computers, Programming, General Technical Tinkering
XCCP describes itself as an Extended Console Command Processor for CP/M. It supports the 8080 and v1.0 was released by Anton R. Fleig in 1984. Like EPEX, XCCP doesn't require installing so we can begi| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Epex is an evironment extension for CP/M. It stands for Environmental Processing EXecutive, and v1.1 was released by James H. Whorton in 1986. It can make using CP/M much more comfortable at the cost| TechTinkering - Retro Computers, Programming, General Technical Tinkering
There are many utilities available for CP/M to compare the differences between files and to distribute those differences. All the utilities in this article can be found on the Walnut Creek CD. Binary| TechTinkering - Retro Computers, Programming, General Technical Tinkering
If you have good eyesight, a well-tuned display and patience it is possible to use 80 columns in software on the VIC-20. This is really just an experiment but considering the limitations of the Vic I| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Breakout style video games were pretty popular at one time both at Arcades and on home computers. The games are based on a simple concept where you have to destroy a group of 'bricks' at the top of t| TechTinkering - Retro Computers, Programming, General Technical Tinkering
With a little lateral thinking and by putting the television on its side we can create a 64 column sideways text mode on the VIC-20. This article will demonstrate this and show how it is done. Previo| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Hamurabi is probably the best known land and resource management game on CP/M. However, there are a few other similar text-based games that sought to extend the concept such as Dukedom and Kingdom. T| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Word processing is possible on the VIC-20 and can be surprisingly comfortable despite the small screen text area. Here I will show a variety of word processors each of which handles the 22 column rest| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Getting the address of a BASIC variable can be useful if you want to pass data to a machine code routine or want to access the bytes of a variable directly to improve speed and reduce garbage collectio| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Saving and loading memory is quite easy on the VIC-20 once you know how. However, it isn't obvious how to do this and therefore this article will present a few simple ways of doing it from BASIC and A| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Lots of utilities make use of .LBR (Library) files to provide extra facilities such as the ability to run commands from archives or mount them as if they were drives. This article shows some more adva| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The .LBR (Library) file format was the most common form of multi-file archive on personal computers at one time. It was created by Gary P. Novosielski in 1982 for use by his LU (Library Utility) progr| TechTinkering - Retro Computers, Programming, General Technical Tinkering
BASIC programs are stored in memory using a simple structure that we can investigate and manipulate. This article will show how they are stored and contains a BASIC program to go through each line of| TechTinkering - Retro Computers, Programming, General Technical Tinkering
VICMON is a machine language monitor released by Commodore in 1982 and is great for programming the VIC-20. Its interactive nature means that it can often be quicker to develop via this rather than us| TechTinkering - Retro Computers, Programming, General Technical Tinkering
BASIC programs often contain machine code routines but they take up quite a lot of space in BASIC. An interesting way to reduce the amount of space that they take is to store the machine code in REM s| TechTinkering - Retro Computers, Programming, General Technical Tinkering
After a transient program terminates on CP/M it's often possible to re-execute it in memory without having to reload it from disk. This is a great little trick if using slow disks as it's much quicke| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The VIC-20 is a very flexible little machine and allows us to choose which area of memory represents the screen map. One interesting thing we can do is use this to visualize a section of memory such| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The unexpanded Commodore VIC-20 only had 5K of RAM and therefore creative ways had to be found to maximize the available RAM. The display memory would use some of this memory and therefore one option| TechTinkering - Retro Computers, Programming, General Technical Tinkering
I love ED on CP/M. It's often derided but I think it's just misunderstood and with a little practise its true value can shine through. It's elegant, easy to learn and only has about 25 commands but t| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The C64 used a fatter double-width font because the video quality of early VIC-IIs wasn't very good. Therefore they had to make the C64's font fatter than the VIC-20's. However, this fatter font look| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Pilot was created by John A. Starkweather in the early 1960s as a programming language for Computer Assisted Instruction. It has often been compared to Logo because of its use with children. However,| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The Walnut Creek CD has a number of images on it from the 1980s and this article displays a selection of the Commodore C64 images that can be found on the CD. The quality of some of these pictures is| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The Walnut Creek CD has lots of images on it from the 1980s and this article displays a selection of the .RLE images that can be found on the CD. Where there are duplicates they are only shown once. .| TechTinkering - Retro Computers, Programming, General Technical Tinkering
CP/M is by default a text-only affair. However, many of the machines that can run CP/M have hardware that would allow them to display graphics. As BBSing started to grow so too did the distribution o| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The VIC-20 introduced many people into the world of BBSing, but only a few of the many terminal programs that were available for the Vic have survived. They each have their own pros and cons and here| TechTinkering - Retro Computers, Programming, General Technical Tinkering
I have created a SUBLEQ Virtual Machine for the Commodore VIC-20. SUBLEQ is a computer architecture that has only one instruction: SUBLEQ. The instruction stands for SUbtract and Branch if Less than| TechTinkering - Retro Computers, Programming, General Technical Tinkering
SUBLEQ has to be one of the easiest architectures to implement in either software or hardware and this is the main reason for its design as a teaching aid. It has only one instruction, hence why it is| TechTinkering - Retro Computers, Programming, General Technical Tinkering
As soon as you pick up this coffee table style book you know that you're in for a treat. A quick flick through reveals page after page of beautiful photos accompanied by well layed out text describing| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Mouse is an interpreted stack orientated language designed by Peter Grogono around 1975. It was designed to be a small but powerful language for microcomputers, similar to Forth, but much simpler. On| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Sweet 16 was created by Steve Wozniak to reduce code size and make it easier to handle 16-bit pointers and arithmetic for his Apple Integer BASIC. He wrote it around 1977 and referred to it in an arti| TechTinkering - Retro Computers, Programming, General Technical Tinkering
If we are writing 6502 machine code and want to to create a routine or program that can be placed in any location then we have to create Position Independent Code (PIC) or make the code relocatable. H| TechTinkering - Retro Computers, Programming, General Technical Tinkering
To make machine language programs more friendly it's 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 a| TechTinkering - Retro Computers, Programming, General Technical Tinkering
I quite enjoy designing machine language routines on paper and then hand assembling them. For many people this would have been their only option until they got a more advanced machine language monitor| TechTinkering - Retro Computers, Programming, General Technical Tinkering
When programming using machine code there are a few useful aids that can make it easier to do. I have created a couple of tables for the 6502 that can make the process easier. They are based on table| TechTinkering - Retro Computers, Programming, General Technical Tinkering
petcat is a utility provided with the VICE Commodore emulator that you can use to convert Basic source code contained in ASCII text files to .PRG files or vice versa. It is also able to convert ASCII| TechTinkering - Retro Computers, Programming, General Technical Tinkering
To make the most of the limited amount of memory on the VIC-20, we can increase and decrease the screen size depending on our program's priorities and what we want to achieve. If we increase the size| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The VIC-20's VIC chip provides a simple yet flexible video display and one of the features that can be quite useful is the ability to alter the picture origin on the screen. This feature allows us to| TechTinkering - Retro Computers, Programming, General Technical Tinkering
I recently came across an interesting program called DABAR to drill Hebrew vocabulary. The program works in a similar way to flash cards, by displaying a word in Hebrew and then asking for its English| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The VIC-20 had a number a spreadsheet programs released for it which despite the limited resources of the Vic could actually be quite usable. The two best known are SimpliCalc and PractiCalc, but ther| TechTinkering - Retro Computers, Programming, General Technical Tinkering
There are a number of programs that allow you to use 40 columns of text from Basic on a Commodore VIC-20. This can be useful as by default the Vic's screen is 22 columns by 23 rows. They are supplied| TechTinkering - Retro Computers, Programming, General Technical Tinkering
My favourite traditional board game is Backgammon and the best version I have found for CP/M is The Peelgrunt Game of Gammon IV, v2.0 released 1st April 1986 by David C. Oshel. It is available on the| TechTinkering - Retro Computers, Programming, General Technical Tinkering
There are lots of great alternatives to the standard CP/M DIR command, which add extra functionality and combine features that normally have to be accessed through other CP/M commands such as STAT or S| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Mission: Impossible simulates a foreign espionage mission based on the TV series. Your mission, should you decide to accept it, is to recover the objects or person taken by enemy agents and hidden in| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Hunt The Wumpus was created by Gregory Yob in 1973 after seeing some of the hide and seek style games distributed by the People's Computer Company. Games such as Hurkle, Snark and Mugwump were all ba| TechTinkering - Retro Computers, Programming, General Technical Tinkering
CP/M helped provide a consistent console interface for the user by supporting a number of standard control characters through the BDOS console functions. This was great for the user and made life much| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Using Vice to emulate a Commodore 128 running CP/M works very well, but it isn't easy to get CP/M files directly onto and off a .D64/.D71 disk image. The easiest way to do this under Linux is to use c| TechTinkering - Retro Computers, Programming, General Technical Tinkering
z80pack is great for creating an emulated CP/M system. It can either be used to create a general CP/M system or can emulate a specific system such as an IMSAI or ALTAIR including a graphical front-pan| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Instrument Flight Simulator is a text mode flight simulator for CP/M which uses standard ASCII characters to display an instrument panel for the plane. The aim of the game is to land the aircraft safe| TechTinkering - Retro Computers, Programming, General Technical Tinkering
CP/M has a number of interactive file managers that can be used to make it easier to handle common file operations rather than using the command line driven commands supplied with CP/M such as: DIR, ER| TechTinkering - Retro Computers, Programming, General Technical Tinkering
In 1979 the University of Tennessee/Knoxville's Computer Science Department released Felix v2.1 for CP/M, which is available on the Walnut Creek CD. It aimed to provide a basis for computer animation| TechTinkering - Retro Computers, Programming, General Technical Tinkering
CP/M has the ability to handle lots of different compression and archive formats which was important due to the limited capacity of floppy disks and the cost of downloading/uploading files on BBS's. T| TechTinkering - Retro Computers, Programming, General Technical Tinkering
There are lots of text viewers on CP/M and I want to show the three that I use most often. I have recently been going through the Walnut Creek CD to see if I can find any better text viewers, but afte| TechTinkering - Retro Computers, Programming, General Technical Tinkering
CP/M is a single tasking operating system and having grown-up with single tasking systems this has never really been a problem for me. There is style of program that would make my life easier, however| TechTinkering - Retro Computers, Programming, General Technical Tinkering
There are a few machines I'm quite interested in comparing so I decided to create a simple Basic benchmark to get an idea of their relative speed. The benchmark tests 7 aspects and is inspired by qsbb| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Ornament is a Tcl template module that allows you to define, parse and compile a template to produce a script which can then be run using a safe interpreter. The idea came from the Templates and subst| TechTinkering - Retro Computers, Programming, General Technical Tinkering
There are lots of different programming challenges, but this year one in particular has caught my attention and I have decided to take part. Advent of Code starts 1st December with daily programming p| TechTinkering - Retro Computers, Programming, General Technical Tinkering
The premise of this book is that the 60s/70s counter-culture led to the personal computer revolution. I think the book demonstrated well how this influenced SAIL and how the Augment lab innovations led| TechTinkering - Retro Computers, Programming, General Technical Tinkering
Geary is a lightweight email client inspired by gmail's interface. Its simple minimalistic interface is quite pleasant to use and initially I was really pleased to switch to it from Thunderbird. Howe| TechTinkering - Retro Computers, Programming, General Technical Tinkering
With F#, the list often feels like the default choice of data structure. It is immutable and hence easy to reason about, however its use can come at a great cost. If you are using lists to process la| TechTinkering - Retro Computers, Programming, General Technical Tinkering
With the new package management system for Racket, there is a need to host documentation for the package somewhere. Github allows you to host web pages, and hence a package's documentation, by putting| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 n| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 its popularity today. The| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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,| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 ove| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 it| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 19| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 assoc| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 scrip| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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, R| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 w| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 ou| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 unex| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 field| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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.| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 emul| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 fol| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 proble| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 desig| TechTinkering - Retro Computers, Programming, General Technical Tinkering
When I first came across SUBLEQ, 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 im| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 f| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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| TechTinkering - Retro Computers, Programming, General Technical Tinkering
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 j| techtinkering.com
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 g| techtinkering.com