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!
You might think the DOS ROM of the Commodore 1541 disk drive has been analyzed to death. But here are two new resources:
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!
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:
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.
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.
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
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.
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.
The text screen of the Commodore 64 has a resolution of 40 by 25 characters, based on the hardware text mode of the VIC-II video chip. This is a step up from the VIC-20’s 22 characters per line, but since computers in the professional segment (Commodore PET 8000 series, CP/M, MS-DOS) usually had 80 columns, several solutions – both hardware and software – exist to allow 80 columns on a C64 as well. Let’s look at how this is done in software! At the end of this article, I present a fast and full-featured open source implementation with several different character sets.
This is the video recording of “The Ultimate Game Boy Talk” at 33C3.
I will present “The Ultimate Game Boy Talk” at the 33rd Chaos Communication Congress in Hamburg later in December.
Major GEOS applications on the Commodore 64 protect themselves from unauthorized duplication by keying themselves to the operating system's serial number. To avoid tampering with this mechanism, the system contains some elaborate traps, which will be discussed in this article.
In mid-1990, the floppy disk of special issue 55 of the German Commodore 64 magazine "64'er" contained the "Amica Paint" graphics program – which was broken beyond usefulness. I'll describe what went wrong.