Cenbe's Commodore 64 Pages (last updated 2025-08-30)

Flyer (red card)

1541 Ultimate V1 (CS8900a)

I enjoy using and programming the Commodore 64 (one of the early home computers, for those of you who weren't there), and have a good collection of hardware and software. I'm mainly interested in programming languages and operating systems (especially GEOS and GeckOS). (Scroll this page down for more content links; there's also a picture and description of my setup.) If you want, you can email me (cenbe at protonmail dot com). I also maintain the #c64friends IRC channel on Libera.

For some time, I've been working on a disk image library called d64py, written in Python. It was used to write the Disk Wrangler, a disk image explorer that's very good with GEOS files. I made a video about it showing the things it can do, and you can find the source code at Codeberg. The d64py libraries were also used to create a web app for exploring and downloading the GEOS fonts in my collection; it can also be found on Codeberg.

I showed a 2.0 version of geoGopher at VCFMW 2021; this version uses a GEOS network driver I wrote for the 1541 Ultimate II+ and Ultimate 64 based on Scott Hutter (xlar54)'s code. Version 2.1 was released on 2021-09-27; follow the link for lots more info.

A big topic of interest these days is network cards for the Commodore 64. In the beginning, there were Ethernet cards that used the CS8900A chip ("RR-Net compatible"). The big problem with these cards is that they're just dumb hardware, and require a TCP/IP stack running on the Commodore 64, which is quite a stretch. Apart from the speed and memory issues, this is not the Commodore way of doing things! That sort of processing should be offloaded, as it is with the disk drives. But people still did amazing things with those cards, like Jonno Downes' BASIC extenders Kipper BASIC and BASIC on Bails, which let you write networked programs using BASIC commands. Follow the link to see disk images, API docs, and a copy of the presentation I gave at ECCC 2010.

Later, there were cards that used the WIZnet W5100 chip, which has an on-board network stack. There was also the Flyer, which implements networking as I/O commands sent to device #7 on the serial bus, but it never really caught on and is no longer made. A shame, because the design made it possible to write networked programs even in BASIC, just by using standard serial bus commands. I gave a presentation about this card at ECCC 2012, and discussed a reusable PROMAL module I wrote for the Flyer in my talk on that language at ECCC 2014. On the right (click to embiggen) are pictures of my machines with some of these older cards.

There are now wifi adapters available as well, based on the ESP8266 chip, although they generally seem to be nothing more than RS232-to-TCP/IP adapters rather than true network devices (there also seems to be little standardization of AT command extensions and even RS-232 implementations). Among them are Schema's Commodore Wi-Fi Modem, CBMSTUFF's WiModem, and Alwyz' Strikelink. You can also build your own Strikelink, or use Bo Zimmerman's design. A card using Bo's firmware is available here, along with some very complete documentation. More information on WiFi cards for the Commodore 64 can be found here.

But the best networking available for the Commodore 64 is in the Ultimate devices from Gideon Zweijtzer (1541 Ultimate II+, Ultimate 64). The networking in these devices is so easy to use and so reliable that "Ultimate" networking should be just as much a standard for Commodore users as JiffyDOS is. This is the standard, folks. Although the networking APIs are not well documented, like everything else Commodore, it's been reverse-engineered: Scott Hutter ("xlar54") made a library that you could use as is or adapt, depending on your language preferences (it's written in C). The docs/ section of that page includes instructions on how to do things at the register level. I wrote an Ultimate GEOS driver in 6502 assembler based on Scott's work for geoGopher; that page includes the driver's source code as a PDF.

Here's what you can find here: