Propeddle: A Commodore PET/CBM Replica using a 6502 and a Propeller

http://www.savagecircuits.com/forums/sh ... -Propeller

Thanks for posting the link, ChuckT. As you can see I have an account here too now.

FYI: I updated the thread with a Theory of Operations article last night.

Now I'm going to work on making it work as "advertised"

Enjoy!

===Jac

PS It's not really just a PET/CBM replica anymore, it should be able to replicate many other early 6502 systems.

Hi Jac,

Welcome to the forum. I like you board and share you love for computers.

How long have you been building the Propeddle?

Please tell us what you want us to know about it.

Chuck

Hi Chuck,

I've been thinking of making a PET/CBM Replica since I found out about other replica computers like the MicroKim, the Replica1, the C64DTV and the C-One. I wondered if anyone had thought of making a PET/CBM replica before, but the only thing I found at the time were Andre Fachat's 6502 system and Dennis Ferron's Prop-6502 project.

I already had a MicroKim and a 32K expansion board for it, and for Christmas I got a Pocketerm, all from brielcomputers.com. I bought a breadboard and two 74LS244s at Fry's and then I had all the hardware I needed to breadboard my version of the Prop-6502 project, only I was using VGA instead of TV.

The next step would be to implement a PETSCII VGA display, and then it would be a matter of downloading a ROM image from Zimmers and some software for the Propeller to make it run. Unfortunately during testing of my PETSCII display driver, I found out that it wasn't going to be possible to run the 6502 if all the work was done on one cog. But it wouldn't be easy to divide all the work over multiple cogs either, because it took so long to read the address from the 6502 through 8 bits of I/O and shift it into place.

So I set out to modify the schematic so it would use all pins 0-15 of the Propeller for the address bus of the 6502. I made a schematic based on the GadgetGangster Propeller Platform because it would be easy to fit everything into Eagle Light (basically I didn't need to design anything that was Propeller related). I also routed a PCB and sent it off to Dorkbot PDX PCB service.

I now have one circuit board that has all the parts on it (and two unpopulated PCB's) and I'm in the process of writing software to control the 6502 and emulate other parts like video memory. I will need at least two cogs to do it but it should be easy to let them work together.

There are some small things I want to change to the hardware before sending the board off for production, so it's not available for purchase yet. I want to make sure the software will work too.

I'm surprised to see so much attention for my project. I will try not to let anyone down, but please be patient! I don't have much spare time and to say that my Real Life is very turbulent right now, would be an understatement. So hang on in there, and thanks for reading!

===Jac

The SavageCircuits.com website is down, but I'm building a website with all the information at http://www.propeddle.com%20now.

The original thread is on the Zappbots forums at http://z13.invisionfree.com/zappbots/index.php?showtopic=37. Thanks Zappman for posting this.

===Jac