We are going back to breadboarding for designing what will be the base for the new Steckschwein computer core. By “core” we mean CPU, RAM, ROM and the glue logic which will be accommodated in the ATF1508 CPLD. In order to communicate with the outside word, we also count the 16C550 UART as part of the core.

Design goals

Our main design goals are:

• Integrate SPI into the CPLD
  Using a hardware based SPI implementation similiar to the SPI65, but tighly integrated into the CPLD will be an efficient use of the CPLD resoures and will provide a much more performant SPI bus as opposed to the current semi-bit-banged solution. This way, it will be much more performant to add more SPI based components such as USB host or networking.
• Implement a priorising vectorising interrupt controller \ This will improve interrupt handling by assigning a dedicated ISR routine per interrupt source instead of one system ISR.

Other changes/optimizations

Other things that will be optimized are:

Since we introduced our new banking logic to access 512k RAM, our glue logic is being accommodated by a Xilinx XC9572 (without XL) CPLD. This component has long been deprecated when we started using it. We chose it because it was what we had available. The upgrade path would be the successor family XC95..XL. Those have been rather expensive lately, and finally AMD/Xilinx axed their whole CPLD line in 2024, leaving us at a dead end. Where do we go from here? The market for CPLDs is not exactly growing. Only a few manufacturers are still actively producing them.

We talked to Martin Wolf from Golem.de about our Project, how it came to be, and of course about our version of Pacman.

Listen to our Episode (in German) here!

After we moved this website to Codeberg Pages, we now finished moving our Repositories to www.codeberg.org.

The resources page has been updated with the new URLs.

Our repositories on GitHub will remain available as push mirrors, but may vanish at some point.

Codeberg is a non-profit, community-led effort that provides Git hosting and other services for free and open source projects.

At this year’s installment of the Vintage Computer Festival Europa we talked about how the Steckschwein came to be in its current incarnation. Marko presented his feature complete implementation of Pacman - the only one for 6502 based systems that replicates the look and the behaviour (including bugs) of the original arcade almost completely.

In case you could not attend our talk or even VCFe, you still can download the Steckschwein slides and the Pacman slides.

This year’s installment of the Vintage Computer Festival Europa is - again - a special one for us: VCFe 24.0 will be focused around “50 years of 6502”!

So be prepared for lots of 6502 related and also unrelated exhibitions and talks!

We will of course be there, too, presenting Marko’s Pacman implementation - the only one for 6502 based systems that replicates the look and the behaviour (including bugs) of the original arcade almost completely.