assembly

Extending Commodore 64 BASIC

Jim Lawless
The original version of this post was published on March 16, 2014. Back in the day, I used to write machine-language subroutines for the Commodore 64 that I would then call from a main program written in BASIC. I found it easier to use BASIC as the higher-order controller over a set of ML functions that usually did things for which CBM BASIC 2.0 was not well-suited. In one case, I wrote an Xmodem file-transfer protocol handler.

Understanding TRS-80 .CMD Files

Jim Lawless
I had originally published this text on Sunday, November 8, 2009. It’s seen a couple of revisions. There’s some C code in this post, but the main point of the post is to provide a way to dump TRS-80 binary CMD files. The source code for all files can be found here: https://github.com/jimlawless/readcmd I’ve begun to use TRS-80 emulators to recapture some of the programming experiences of my younger days. The emulator I’m currently using under Windows is trs80gp which can be found here:

Learning Z-80 Assembly Language on the TRS-80

Jim Lawless
Originally published on: Sun, 08 Nov 2009 My first computer was a second-hand TRS-80 Model I with 16K of RAM and a cassette-recorder for auxiliary storage. I was 17 years old when I received this computer in the Fall of 1982. My goal? Like many kids my age at the time, I had intended to write a video game or two and live happily on the riches that would befall me.

Jim Butterfield : The Commodore Guru

Jim Lawless
Originally published in the Commodore Hacking (C=Hacking) electronic magazine #14, November 1996. This post has been reprinted in Commodore Free magazine and other e-magazines. Jim Butterfield passed away on June 29th, 2007 after a long battle with cancer. I grieve with the family and the legions of techies who looked upon Jim as a mentor via his articles and ongoing contact with the Commodore community. Rest in peace, Mr. Butterfield.

Speaking with Don French : The Man Behind the French Silk Assembler Tools

Jim Lawless
Originally posted 5-21-2004. In the early days of 8-bit computing, a programmer’s most often-used tool was the assembler. Due to memory constraints, many of the early 8-bit machines could not run a full assembler. At best, one could hope for some sort of machine-language monitor that would include a mini-assembler and a disassembler. That was … until Don French came along and implemented a symbolic assembler on the unexpanded VIC-20.

An Interview with Game Developer James Hague

Jim Lawless
This post was originally published in 1999. Being a bit of a video-game and classic computer enthusiast, I recently purchased the electronic book Halcyon Days - Interviews with Classic Computer and Video Game Programmers. Note: In 2002, this book was made available to read freely here: https://www.dadgum.com/halcyon The author of the book, James Hague, is himself a game developer. Since I noticed that his complete bio was missing from the text, I asked if he’d permit me to interview him.

Ancient Devtools

Jim Lawless
When I first began using microcomputers in the late 1970’s, development tools for 8-bit machines were precious and mysterious commodities. Most of these sorts of tools that looked to be useful were very expensive. My usage of most of these tools was driven by budgetary constraints. The Gateway Drug : BASIC All it really took to pique someone’s interest in microcomputers was to show them a simple program such as: