Some Assembly Required
geoWrite is a WYSIWYG rich text editor for the Commodore 64 GEOS operating system. I created a reverse-engineered source version of the geoWrite 2.1 for the C64 (English and German) for the cc65 compiler suite:
In the series about the internals of the geoWrite WYSIWYG text editor for the C64, this article discusses how the app consolidates keyboard input to keep up with fast typists.
In the series about the internals of the geoWrite WYSIWYG text editor for the C64, this article discusses its efficient cross-application cut/copy/paste implementation.
In the series about the internals of the geoWrite WYSIWYG text editor for the C64, this article discusses how its file format allows the app to efficiently edit documents hundreds of KB in size.
In the series about the internals of the geoWrite WYSIWYG text editor for the C64, this article discusses what was required for the German localization.
In the series about the internals of the geoWrite WYSIWYG text editor for the C64, this article discusses the geoWrite copy protection.
In the series about the internals of the geoWrite WYSIWYG text editor for the C64, this article discusses how it makes maximum use of the scarce zero page space.
In the series about the internals of the geoWrite WYSIWYG text editor for the C64, this article discusses the font manager’s system of caches for pixel fonts.
In the series about the internals of the geoWrite WYSIWYG text editor for the C64, this article discusses how the app manages to extend its usable RAM by 5 KB using a custom screen recovery solution.
geoWrite is a WYSIWYG rich text editor for the Commodore 64 GEOS operating system, which runs with a total of just 64 KB of RAM. In the series about the internals of geoWrite, this article discusses how it manages to fit 52 KB of code into the available 23 KB of application RAM.
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.
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!
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.
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.
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!
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.
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:
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.
“The Wave” is a Web Browser for GEOS (with the Wheels extension) on C64/C128 machines with a SuperCPU and a RAM extension.