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!
The C128 source dump over at zimmers.net that appeared recently contains source for a version 2 kernel, which was never released. The known versions are 0 and 1. Let’s see whether we can reconstruct the ROM image!
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:
The well-known Serial Bus (aka Serial “IEC” Bus) of the Commodore 64 that connects to disk drives such as the 1541 is just one variant of a whole family of busses and protocols used by the line of 8 bit Commodore machines from the PET to the C65. This is the first article of a multi-part series on the Commodore Peripheral Bus family.
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.
For decades, PC users have been able to relax by watching the computer defragment a disk. Now C64 users can do the same! Introducing “defrag1541”, a disk defragmentation tool for C64 and 1541.
The Commodore Datasette recording format is heavily optimized for data safety and can compensate for many typical issues of cassette tape, like incorrect speed, inconsistent speed (wow/flutter), and small as well as longer dropouts. This makes the format more complex and way less efficient than, for example, “Turbo Tape” or all other custom formats used by commercial games. Let’s explore the format by writing a minimal tape loader for the C64, optimized for size, which can decode correct tapes, but does not support error correction.
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
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.