C64
TopDesk 1.3 GEOS64/128 Original Source
Thanks to Falk Rehwagen and Jürgen Heinisch, the original source of the TopDesk file manager for the GEOS operating system of C64/C128 is available.
Run CP/M on your C64 – using Emulation!
In this episode of computer archeology, we deconstruct a very interesting case of borrowing code from multiple places – but first try this D64 disk image with any Commodore 64 emulator or a real C64:
C64 CP/M Cartridge
The cartridge that makes a C64 a “dual processor” computer: Commodore’s CP/M cartridge for C64 contains a Z80 CPU and comes with version 2.2 of the CP/M operating system. Here are some pictures.
Commodore Bildschirmtext II Decoder Cartridge
Here are some pictures of the outside and the inside of a Commodore Bildschirmtext II Decoder Cartridge for the C64 – a 6800-based computer connected to the expansion port!
The Commodore IEEE-488 Cartridge for C64
Commodore 64 disk drives were usually connected through the slow serial bus. This article shows some hi-res photos of the Commodore “IEEE-488 cartridge”, which made the faster PET drives available for the C64.
Final Cartridge III with GEOS
The Final Cartridge III is great: It comes with a disk speeder, BASIC extensions, an excellent monitor – and an impressive, but ultimately useless GUI, because there are practically no applications for it. Let’s replace the FC3 GUI with GEOS!
Commodore MAX Machine
Here are some hi-res pictures of the Commodore MAX machine (aka Ultimax or VC-10), a stripped-down game console variant of the Commodore 64 that was briefly available in 1982.
Illegal Opcode Support for the Final Cartridge III Monitor
The monitor built into the Final Cartridge III is one of the best ones for the C64. Some of its unique features are:
Commodore Peripheral Bus: Part 4: Standard Serial
In the series about the variants of the Commodore Peripheral Bus family, this article covers the lowest two layers (electrical and byte transfer) of the “Standard Serial” bus as found on the VIC-20/C64 as the main bus, but also supported by all other Commodore home computers.
GEOS Demo [GIF]
The GEOS operating system for the Commodore 64 achieved to replicate much of the GUI of the original Macintosh on a 1 MHz 8 bit CPU with just 64 KB of RAM. The GEOS Demo is a presentation by Berkeley Softworks (BSW), the creators of GEOS, to showcase the features of GEOS and BSW’s applications.
Das Maschinensprache-Buch zum Commodore 64 [PDF]
Reconstructing the GEOS 2.0 (de) Master Images from a Pile of Broken Disks
I have this pile of broken GEOS disks that were sent in for replacements. In two previous articles (1, 2), I explored the reasons why the disks broke. Now let’s be constructive: Can we reconstruct the original bits by combining the correct parts? This article shows how it is possible with the help of a small tool that combines the good parts of several broken disk images.
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.
A GEOS Speed Zone Bug? (Why Do C64 GEOS Boot Disks Break, Part 2)
I happened to come across 50 original German GEOS 2.0 disks that were broken and sent in for replacement. In the first part, I covered the disks that were broken probably due to user error. Now let’s look at the read errors on the remaining disks. As it turns out, there might be a bug in GEOS that caused the boot disks to break!
Why Do C64 GEOS Boot Disks Break? (Part 1)
The most fragile things in the universe (next to C64 PLA chips) are C64 GEOS boot disks. Because of its copy-protection, the “Graphic Environment Operating System” had to be booted from the original disk every time. The disk failed so often that the box came with a second “backup” boot disk.
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:
Das neue Commodore 64 Intern Buch [PDF]
Archiving C64 Tapes Correctly
It’s pretty simple to archive Commodore 64 tapes, but it’s hard if you want to do it right. Creating the complete archive of the German “INPUT 64” magazine was not as easy as getting one copy of each of the 32 tapes and reading them. The tapes are over 30 years old by now, and many of them are hardly readable any more.