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.
Prototype Commodore 232 and 264 Computers
Here are some hi-res photos of the Commodore 232 and Commodore 264 prototypes. The C-232 and C-264 were two1 of the planned models of the TED series, but neither shipped. The C-264 became the Plus/4, with productivity software preinstalled in ROM, and the low-lost C-232 was replaced by the even lower-cost C16 and C116 models.
Third Party Disk Drives for the C64: The “Technica”
I have previously analyzed the ROM images of some third party disk drives for the Commodore 64: The result was that most of them were just using the original binaries with some obfuscation, and some with some added features. This time, let’s look at another drive, the “Technica”, which is a little special in this regard.
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.
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!
Visualizing Commodore 1541 Disk Contents
G64 files are C64/1541 disk images that contain all bits as they are physically laid out on the 5¼-inch floppy disk. Let’s visualize them!
Building the Commodore TED Kernal with Modern Tools
The original Commodore TED (C16, C116, Plus/4) source code has recently appeared on zimmers.net. It is also available in my Commodore Source Code git repository.
Building the Original Commodore 1541 DOS Source
You might think the DOS ROM of the Commodore 1541 disk drive has been analyzed to death. But here are two new resources:
Analyzing the ROMs of Third Party Disk Drives for the C64
Most Commodore 64 users had a 1541 disk drives, but there were always also third part options. Most of them claimed full 1541 compatibility, which sounds impossible without using the same ROM. Let’s analyze the ROMs of some third party drives!
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:
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.
INPUT 64 Magazine Complete Archive
The complete archive of the German Commodore 64 magazine INPUT 64 (PDF, tapes, disks) is now available here.
Making Of “Murdlok”, the new old adventure game for the C64
Recently, the 1986 adventure game “Murdlok” was published here for the first time. This is author Peter Hempel‘s “making-of” story, in German. (English translation)
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.
Commodore KERNAL History
If you have ever written 6502 code for the Commodore 64, you may remember using “JSR $FFD2” to print a character on the screen. You may have read that the jump table at the end of the KERNAL ROM was designed to allow applications to run on a all Commodore 8 bit computers from the PET to the C128 (and the C65!) – but that is a misconception. This article will show how
The Ultimate Apollo Guidance Computer Talk [video]
This is the video recording of “The Ultimate Apollo Guidance Computer Talk” at 34C3. If you think it is too fast, try watching it at 0.75x speed.
The Ultimate Apollo Guidance Computer Talk @ 34C3
After The Ultimate Commodore 64 Talk (2008) and The Ultimate Game Boy Talk (2016), my third talk from the “Ultimate” series will take place at the 34th Chaos Communication Congress at Leipzig (27-30 Dec 2017):
62 Reverse-Engineered C64 Assembly Listings
Between 1992 and 1995, I reverse engineered Commodore 64 applications by printing their disassemblies on paper and adding handwritten comments (in German). These are the PDF scans of the 62 applications, which are 552 pages total.