UP9600: How to Bit-Bang 9600 Baud RS-232 on the C64
The user port of the Commodore 64 exposes a TTL-level RS-232 serial port that supports up to 1200 baud1. In 1997, Daniel Dallmann came up with a very sophisticated trick that allowed sending and receiving at 9600 baud2, using slightly different wiring and a dedicated driver. This “UP9600” wiring has become the de-facto standard for all modern accessories, like C64 WiFi modems. Let’s see how UP9600 works.
Free Joystick Extension Cable to Build Your DB9 Competition Pro
This article explains how to convert a “Competition Pro Extra USB” (which you can still buy new) to work with a C64, Amiga or Atari. For the conversion, you need a joystick extension cable like this:
[UPDATE] Converting the “Competition Pro Extra USB” to C64/Amiga/Atari DB9
I updated the instructions to a USB Competition Pro to DB9, so you can use it with a C64, Amiga etc. They now include the new “V3” and “V04T” pinouts and were updated with the use of a joystick extension cable.
Building the Tynemouth Mini PET
Dumping MiniDisc Media
If you have music on a collection of MiniDisc media and want to finally copy the data off onto modern media (or the cloud!), here are simple instructions for some different solutions:
Tynemouth Minstrel ZX80 Clone Kit
I have previously shown an unassembled Sinclair ZX81 Kit that could be bought in the early 80s. Today, it is possible to buy a clone of the ZX80 from Tynemouth Software. Here are some pictures.
Converting a Commodore 1541 or 1570 Drive into a 1551
The 1551 is the weird outlier in the family of Commodore disk drives: It is the only drive using the “TCBM” bus instead of Serial or IEEE-488. And what’s even weirder? 1541 and 1570 drives converted into 1551s!
Sinclair ZX81 Kit
Here are hi-res photos of an unassembled Sinclair ZX81 kit, with German assembly instructions.
Converting the “Competition Pro Extra USB” to C64/Amiga/Atari DB9
- Updated 2022-03-09: Added “SL-6603-TWT” pinout. Thanks a lot to Risto K for the infos and the photos!
- Updated 2022-01-26: Added “V2” pinout.
- Updated 2022-01-22: Added “SL-6603-SPORTS-DE” pinout.
- Updated 2022-01-14: Added “SL-6603-SBK” and “KOKA” pinouts.
- Updated 2022-01-06: Added new “V3” and “V04T” pinouts and instructions on how to use a joystick extension cable.
Speedlink makes several versions of the Competition Pro joystick that have all the physical properties and the excellent switches of the original Competition Pro, but come with a USB interface:
Repairing a Commodore 1084S Power Switch
The power switch of the Commodore 1084S tends to break easily. To replace it, you will need a standard “Preh TV3” switch (which can be found online), a screwdriver, a soldering iron, desoldering braid, and some basic soldering skills.