Inside geoWrite – 3: Font Management
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.
Inside geoWrite – 2: Screen Recovery
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.
Inside geoWrite – 1: The Overlay System
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.
Ultimate Commodore Charset / PETSCII / Keyboard Reference
Another addition to the The Ultimate C64 Reference: We’re adding character sets, PETSCII codes and keyboard layouts – supporting eight different Commodore computers.
Ultimate C64 KERNAL API Reference
The Ultimate C64 Reference is growing again: This time, we’re adding the KERNAL API reference – as always, in eleven different versions side-by-side.
Ultimate C64 Memory Map
The system software of the Commodore 64 has been extensively reverse-engineered. Next to disassemblies of the ROM, several “memory maps” have been published: tables that document system variables in the first kilobyte of RAM, and how to tweak the system software with PEEK and POKE. Now, I’m presenting the Ultimate C64 Memory Map: A C64 memory reference that shows eight sources side-by-side.
Typos in the C64 Programmer's Reference Guide: C3PO or C3P0?
The Commodore 64 Programmer’s Reference Guide contains a memory map with a complete description of the zeropage and system variables used by KERNAL and BASIC, but now that we have the original source, we know there are three typos in this table.
Dumping MiniDisc Media
Update 2022: Web MiniDisc Pro can access NetMD devices through the browser and can also download protected files!
The Ultimate Acorn Archimedes Talk [video]
Matt Evans presented “The Ultimate Acorn Archimedes Talk”, the 8th talk in the “Ultimate Talk” series, at the 36th Chaos Communication Congress (36C3).
The Apollo Guidance Computer [video + slides]
I re-did an updated version of my part of the Ultimate Apollo Guidance Computer Talk at VCF West 2019.
Visualizing Commodore 1541 Disk Contents – Part 2: Errors
We have previously visualized the physical layout of C64/1541 disks. In order to understand the encoding and potential read errors, it is more useful to visualize the disks sector-by-sector.
More Original Commodore Source Code
There have been a few new interesting additions to the Commodore Source Code repository, including:
Run CP/M on your C64 – using Emulation!
In this episode of computer archeology, we deconstruct a very interesting case of borrowing code from multiple places – but first try this D64 disk image with any Commodore 64 emulator or a real C64:
Recovering Files from Broken Amiga OFS Disks
extract-adf is a tool for recovering files from broken Amiga OFS filesystem images. It can reconstruct directory hierarchies even for files that don’t have directory entries.
Boxed MOS 6502 CPU
Back in 1975, you could order a boxed 6502 CPU directly from MOS in Norristown, PA. Here are some high-res photos of such a box and its contents.
Bildschirmtext-Demovideos von 1994
This article is about screen captures of the discontinued German online service Bildschirmtext/Btx.
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.