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!
An unmodified Commodore 1541 disk drive cannot transfer the raw bits of a whole track to the computer it is attached to: The Commodore Serial Bus is too slow to transmit the data in real time as it arrives from the read head, and the drive only has 2 KB of RAM, which is not enough to buffer the 8 KB of a whole track.
An empty ribbon of the 9-pin printer Commodore MPS 1550 C (which is mechanically identical with the Olivetti DM 105) can easily be refilled using stamp pad ink. Here is how:
The physical data format on a Commodore 1541 5¼-inch floppy disk as used by the C64 is completely defined in software. The drive’s operating system fits 170 KB on a disk. This article explores different strategies, each with its pros and cons, to fit up to 246 KB.
The Game Boy is turning 30. To celebrate this, I’m releasing the slides of my “Ultimate Game Boy Talk”, which you may use freely. (Please give credit & point me to derived content.)
The new Speedlink Competition Pro Extra USB joystick has all the phsical properties and the excellent switches of the original Competition Pro, but comes with a USB interface. While this is great for use with The64 Mini for example, this joystick can be easily converted into an old-school DB9 joystick to work with Commodore, Amiga and Atari computers and consoles – without giving up the USB interface!
My side-by-side C64 ROM disassembly/commentary page has been completely redone!
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:
In my quest to make the C16 more usable, i.e. more like the environment I’m used to, i.e. a C64 with a Final Cartridge III, I’ve ported the Final Cartridge III monitor to the TED series (C16, C116, Plus/4).
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!