DigicoolThings Forum

Hi, My name is David and I'm a retired electronics design engineer. My work was my hobby and I still enjoy making things but now I do more of what I want. I have several old and new microcomputer systems and other stuff to play with which is a mixture of old and new technologies, I like to mix the two. I've been building a system to exercise old aviation instruments amongst other things. I have an old 6809 system in pieces and hope to shortly resurrect its firmware on a new (or possibly the old) boards. Ive just dusted off an old S3 eprom emulator and studying some old schematics to get going again... Best regards, David.

Hi David. Welcome on-board!

It sounds like we do have some things in common. My work was also my hobby, which is a great place to be, although perhaps with the downside that it can take over your work/life balance (as I let it). But now, we finally have the time to just follow our own passions.

It'd be great to see your old 6809 system and what you do to resurrect it, either as a video, or even just sharing some images?

Have fun!

Greetings, The old 6809 system looks a bit worse for wear and it never was very pretty. I've dusted it off a bit and fixed a few broken wires. I got a bit stuck trying to resurrect it not knowing about the bugs in the 6551 ACIA chip but I should be able to work around this now. There is a hall effect keyboard read by a multiplexor and 6522 and 2x40 character LCD display. A serial terminal can be used too. Firmware is home brew machine code monitor and Fig-Forth. David.

djrm wrote: ↑Wed Aug 21, 2024 10:35 pm The old 6809 system looks a bit worse for wear and it never was very pretty...

Nice. I like how the PCB is a purpose built prototyping board. It appears to nicely route the memory, but leaves most of the rest for prototyping your design. A nice alternative to Wire-Wraping everything, as I did in the early 80's.

Editor wrote: ↑Wed Aug 21, 2024 11:32 pm Nice. I like how the PCB is a purpose built prototyping board. It appears to nicely route the memory, but leaves most of the rest for prototyping your design. A nice alternative to Wire-Wraping everything, as I did in the early 80's.

The board was quite an expensive investment as I was not earning at the time. The back isn't pretty either:

The 6809 system was an offshoot from my OSI C1P 6502 expansion board which also had figForth on a home made board. This one plugged into the expansion socket of the C1P. All the eprom hex was typed in by hand on the C1P monitor and saved to cassette, the glue code was hand assembled.
Things have moved on since then ... My next 6809 project will have the monitor and low level drivers written in C with minimum assembler support functions. I intend to use an 8042 PC keyboard interface and have one of my existing character / graphic LCD panels with T6963 driver, eventually moving over to a TMS9918 display.

Old 6809 system keyboard:

The ribbon cable plugs onto the CPU card where row / column data is decoded into ascii by software.
(testing image host)

Thanks for posting these photos. It's awesome to see these old boards from somebody else's early days.
I know thay all have significant importance in thier ability to revive fond nostalgic personal memories!

I do like the keyboard! It takes me back to when I used to wire up surplus keyboards in a 8 x 8 matrix, for software scanning from the two 8-bit ports of a PIA, for up-to 64 keys. This was before I eventually got hold of the really useful MM5740 keyboard encoder chip (MM5740AAF rings the most bells, I still have some around here, somewhere), then I was wiring the same keyboards for the MM5740's matrix, and just reading the parallel ASCII output on a single PIA port.

Yes, so many memories. So much fun as we explored the new "science fiction like" microprocessor technology of the day!

Warning sign on my office door - beware blinkenlights ...

djrm wrote: ↑Mon Aug 26, 2024 10:51 am Warning sign on my office door - beware blinkenlights ...

Ha! Love it!