Building and Hacking on the C64 KERNAL & BASIC with Modern Tools
The original Commodore 64 KERNAL and BASIC source code has been available for a while. It used to be built using Commodore’s assembler of a PET.
BASIC
Ultimate Commodore 64 BASIC & KERNAL ROM Disassembly
My side-by-side C64 ROM disassembly/commentary page has been completely redone!
Original Commodore Source Code Collection
Over the years, the ROM source code of many Commodore computers and peripherals has appeared. I have been collecting them in a git repository here:
Commodore 64 BASIC inside your USB Connector
Tomu is a super cheap Open Source Hardware 24 MHz ARM computer with 8 KB of RAM and 64 KB of ROM that fits into your USB connector! Of course I had to put Commodore 64 BASIC on it, which can be accessed through the USB-Serial port exposed by the device.
Murdlok: A new old adventure game for the C64
Murdlok is a previously unreleased graphical text-based adventure game for the Commodore 64 written in 1986 by Peter Hempel. A German and an English version exist.
Reconstructing Some Source of Microsoft BASIC for 8080
Microsoft BASIC for 6502 exists digitally in source form – the older version of the Intel 8080 CPU only exists on paper though: as a printout in the archives of Harvard University. Some snippets of the code are public though:
Comparative C64 ROM Disassembly Study Guide
The Commodore 64 ROM has been subject to immense reverse engineering. Many commented disassemblies were published over the decades, scattered over different media such as books, magazines, disks, and later, the internet – and there are even some commentaries that apply to the C64 ROM, but were written with other systems in mind that shared Microsoft’s BASIC interpreter.
Fully Commented Commodore 64 BASIC ROM Disassembly – based on Microsoft’s Source
On my quest of collecting as many commentaries on the Commodore 64 ROM at pagetable.com/c64rom, we have gathered Lee Davison’s excellent commentary, the German de facto standard by Data Becker, and an adaptation of Bob Sander-Cederlof’s Apple II ROM commentary, all in the same cross-referenced HTML format.
Microsoft BASIC for 6502 Original Source Code [1978]
This is the original 1978 source code of Microsoft BASIC for 6502 with all original comments, documentation and easter eggs:
Fully Commented Commodore 64 BASIC ROM Disassembly – based on Applesoft!
In our series about C64 ROM commentaries (English version by Lee Davison, German version by Data Becker), I’m now presenting a most unusual C64 ROM commentary – based on a commented disassembly of the Apple II ROM.
Fully Commented Commodore 64 ROM Disassembly (English)
After last week’s German C64 ROM disassembly from the “64 intern” book, I have now also converted Lee Davison’s commented disassembly into the same format.
Fully Commented Commodore 64 ROM Disassembly (German)
Whenever I need to look up some code in the ROM of the Commodore 64, I have the choice of the commented disassembly by Marko Mäkelä, the one by Ninja/The Dreams, or the one by Lee Davison – or I can just use my paper copy of “Das neue Commodore-64-intern-Buch“, an excellent line-by-line commentary in German.
Standalone Commodore BASIC on the iPhone/iPad
You might remember the hassle about the Commodore 64 emulator in the iPhone App Store about a year ago: First it was approved, but then pulled again, because it allowed access to the C64’s BASIC – general-purpose interpreters were not allowed. After Apple relaxed this restriction, BASIC was added again.
TI-99/4A BASIC as a Scripting Language
It is a good time for statically recompiled versions of BASIC from old computers. First there was Apple I BASIC. Then came Commodore BASIC. Now, due to overwhelming demand, we’re proud to release TI-99/4A BASIC. For those unfamiliar the TI-99/4A was a home computer by Texas Instruments released in 1981. Unusually for the time it had a 16-bit CPU: the TMS9900.
cbmbasic 1.0 with Plugins
I moved cbmbasic development to SourceForge and released version 1.0, which has the following added features:
Commodore BASIC as a Scripting Language for UNIX and Windows – now Open Source
Update: The source is available at github.com/mist64/cbmbasic
Create your own Version of Microsoft BASIC for 6502
Update: The source is available at github.com/mist64/msbasic
"ROR" in Microsoft BASIC for 6502
If you disassemble any version of Microsoft BASIC for 6502, you’ll find this code in a function that normalizes the (simulated) floating point accumulator:
Bill Gates’ Personal Easter Eggs in 8 Bit BASIC
If you type “WAIT6502,1” into a Commodore PET with BASIC V2 (1979), it will show the string “MICROSOFT!” at the top left corner of the screen. Legend has it Bill Gates himself inserted this easter egg “after he had had an argument with Commodore founder Jack Tramiel”, “just in case Commodore ever tried to claim that the code wasn’t from Microsoft”.