A Visual Defragmenter for the Commodore 64
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.
C64-Artikel in der c’t Retro 2018
This post is about articles I wrote for the c’t magazine in German language. The post is therefore in German.
A Minimal C64 Datasette Program Loader
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.
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.
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.
80 Columns Text on the Commodore 64
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.
Reverse-Engineered GEOS 2.0 for C64 Source Code
The GEOS operating system managed to clone the Macintosh GUI on the Commodore 64, a computer with an 8 bit CPU and 64 KB of RAM. Based on Maciej Witkowiak's work, I created a reverse-engineered source version of the C64 GEOS 2.0 KERNAL for the cc65 compiler suite:
Copy Protection Traps in GEOS for C64
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.
Converting VisAss and F8 AssBlaster Source
If you have developed applications for the Commodore 64 in the 80s or 90s, chances are you still have your old floppy disk with the original assembly sources. If you have used the VisAss or
F8 AssBlaster assemblers, you can use a new command line tool I wrote to convert the encoded binary files into ASCII, so they can be published or you can continue development using modern tools like cc65.
Reverse-Engineered Final Cartridge III Source Code
The Final Cartridge III was one of the major multi-function extension cartridges for the Commodore 64. It contained BASIC extensions, floppy and tape speeders, centronics printer support, screen editor extensions including F-key shortcuts, a monitor, a freezer – and a GEOS-like windowing system called “Desktop”. In all this, the FC3 integrated seamlessly with the look-and-feel of the stock Commodore 64: It did not change anything (same screen colors and banner!), it only extended functionality in consistent ways.
Source of “The Wave” Web Browser for C64/C128 GEOS Wheels
“The Wave” is a Web Browser for GEOS (with the Wheels extension) on C64/C128 machines with a SuperCPU and a RAM extension.
geowrite2rtf, a GeoWrite to RTF converter
geowrite2rtf is a tool that converts Commodore 64/128 GEOS GeoWrite documents into RTF format. Most formatting will be preserved, but some formatting and graphics will be discarded.
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.
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.
The story of 15 Second Copy for the C-64
by Mike Pall, published with permission.