The Cape Computer Club 680x Group System

The Cape Computer Club's been around for a while. In the early eighties, there were groups centered on the 680x, the Z-80, the 6502, and the computers available at the time : Apple, Sinclair, Commodore, TRS-80, Acorn Atom...

I hung out with the 680x group a bit -- they built a 6809 based computer on Eurocards, complete with 256 k dynamic RAM, a floppy disc controller, and graphics.

If you used to belong to the Cape Computer Club in the early eighties, drop me an email.

My 6809 Design of 1990

While still in high school, I played with Motorola D2 and D3 6800 processor boards, and somewhere along the way I fell in love with the 6809. The Cape Computer Club had a fairly active 680x group which designed and built a kickass 6809 system -- Graphics, Dynamic RAM, DAT (That's Dynamic Address Translation, not magtape), the works. At that stage I didn't have the budget to build a similar system, so I kept playing with the 6800 stuff.

A few years later I was a student and had access to design tools (well, smARTWORK, which is better than nothing) and I could easily get double sided (but not through-hole plated) PCBs made.

My first attempt was a close copy of the Sardis 6809 SBC (schematic) which is basically a Color Computer / Dragon minus the Video Display Generator. That board turned out to be unbuildable, due to the lack of though-hole plating, and the project got sidelined.

My second attempt was much simpler. I realised that I could get 64K of RAM using just two chips (32kx8 CMOS RAM), and by that time I had access to peecees that I could use for a terminal, so I didn't need a built-in video display.

Unfortunately I got a few things wrong, and I couldn't get the board to work. Read all about it if you want to.

Microbox II

The Microbox is a 6809 / 6883 (SAM) based design with 64K main RAM and 128K video RAM with a NEC 7220A graphic display controller. Quite a nifty design, even if the PCB is huge. There was also a Microbox 3 and 4 (68000-based), a prototype FPGA-based Microbox2000 (which had limitations) and the Microbox 2020 (MB2K2), which is a good way to get a brand new "6809" machine.

Stuff

General stuff

• An S record converter written by Eric McRae.

C3PO Archives

• C3PO Volume 3 Number 5, June 1980.
• C3PO Volume 4 Number 9, October 1981.
• C3PO Volume 5 Number 5, June 1982.
• Microphile from an unknown volume, describing the C3Bus.

6809 stuff

• I'm using Alan Baldwin's AS6809, which is on C/C++ Users Group volume 292 (4 disks, download here: 1, 2, 3, and 4, or from Eric Smith's 6809 page)
• An article about the design of the 6809 processor (29 pages, 507k pdf file). This article was written by Motorola, and published in Byte.
• An article from Computing Today, April 1981, on the SS50 bus (4 pages, 539k pdf file).
• My 1990 design used the clock schematic from the Motorola Microcomputers MC6809 Course Outline which is wrong. (caution, 3 meg file).
• Microware "6809 Interactive Debug Program" DEBUG09 (7 pages, 707k pdf file).
• One of the CCC members bought a Sardis 6809 PCB and eventually had OS9 running on it. I scanned the schematic.
• Jeff Laughton sent me a link to this fascinating dual-processor 6809 design, with two processors sharing the same memory.
• Optimising 6809 Assembly Code.