Moderators: not sure if this is the right category, or if it's OK to post a link to an open source project for sale as a new member.

Hi there! TangentDelta encouraged me to create an account here and post about a project I've been working on, which has been finalized into a kit. It's a single board computer for the Rockwell R6501Q and R6511Q "single-chip microcmputer" processors. I'm sure a bunch of folks here are already familiar with them, they contain a 6502 core with some modifications and enhancements. The big change is that the I/O registers, internal control registers, and the stack are all in zero page. Zero page is 192 bytes of internal memory in these chips. It seems like a few hobbyists have made boards using these or related Rockwell "single-chip microcomputer" family processors, but there's not a lot of documentation out there. Here's a picture of the first assembled prototype:



The SBC has 32K RAM, 32K ROM in 4K pages, RS-232 buffering, 6 bits of switch register input, two 8-bit I/O ports, and Glitchbus expansion. Glitchbus is a processor-agnostic 8 bit computer bus that I came up with a number of years ago. I haven't implemented much for it yet. It's active when onboard devices aren't talking, and there's a *BMASK line that lets you overlay onboard RAM with stuff on the Glitchbus if necessary. I mapped 0xEF00 - 0xEFFF as the I/O page for Glitchbus I/O (Glitchbus has the concept of separate I/O and memory address spaces).

The proof of concept on the Glitchbus implementation (there's already an 8085-based SBC that talks Glitchbus, and a bunch of prototype stuff around my shop) was to connect my 8255 PPI board and interface using 6502 machine code:



Then I decided to lay out a 32K SRAM board and a backplane, and plug them all together:





Everything mostly worked from the start! There were a few missed pull-ups on the R6501Q SBC. I then dug into the datasheet on the R6511Q and discovered that, from the SBC's point of view, the only difference was that some of the lines that were internally pulled up on the R6501Q weren't on the R6511Q. So, I added some resistors on the back, and got it working:





This board was really designed to be the workshop kit project for VCF East 2020, which of course was going to be 6502-focused. I didn't want to do a plain 6502 SBC since there are lots of those available now. I also happened to have some R6501Qs on hand, and knew I could acquire about 100 more, which would be enough for a kit run. Of course, coronavirus ruined those plans! We've decided to try and do a "virtual workshop" and have folks build kits at home this weekend (yeah, I know, a little late to the party ). The kits are listed here:

https://www.tindie.com/products/glitchw ... -computer/

I'm not selling bare boards at the moment since the goal is to maximize the number of kits we get to people this week, but they'll be listed later on. There's a PDF manual for the SBC, linked from the Tindie listing, which includes the full schematics and technical details on the board. The kit EEPROMs are shipping with a modified version of the Enhanced Woz monitor. TangentDelta did the initial port of it to the R6501Q SBC. We're also working on ports of EhBASIC and Tiny BASIC. EhBASIC is going to take longer, but Tiny BASIC is very nearly ready for testing and should be available this week or next.

TangentDelta captured the livestream, cleaned it up, cut it down, and we've uploaded it to YouTube:

https://www.youtube.com/watch?v=DSpknatBxbc

_________________
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?

Thanks for the cleaned-up stream video, glitch!

Don't worry, we do take appropriate static control precautions. My day-job involves the maintenance and repair of control systems mostly for the semiconductor industry. Any hobby boards I build get the same treatment as boards going into multimillion dollar production machines. Zero failures so far



Most of it is related to the Glitchbus expansion. The full schematic is in the manual, if you're interested!



That was indeed part of the purpose of doing the kit run, I was able to purchase a lot of 100 from one of my regular suppliers. I deal with a lot of sourcing of legacy components.



Thanks! It is indeed one of my workbenches, I run a small business maintaining industrial control stuff, which is often effectively vintage computers. Plenty of 6502-related stuff The little HP supply is one of many older bench supplies I have. They all work excellent after a controls clean-up and, at this point, recapping. The supply most often on the bench is the Lamda FM7202.

No problem, but TangentDelta did most of the work!

We've got the SBC running RSC-FORTH! Configuration 2 runs from just the SBC itself, the 32K memory expansion is required to run Configuration 3. The default ROMFS image also includes a port of Tiny BASIC, too!