6502.org

Hi Everyone

I joined the forum a couple of weeks ago proper as I got stuck on 6522 decoding - and got an answers so quickly and accurately it was awesome.

Anyway, as little gesture of giving back, I thought I would post you my project link (it's on hackaday.io) so you can see how the project is coming along. Happy for any advice, ideas and feedback.

I've been building my homebrew for about 11 months now in the current incarnation. I started very small and simple getting a 6502 to free run etc. The information and links on 6502.org were invaluable and inspiring!

I've made reasonable progress considering I do the odd evening or weekend. The hardware is basically done:
- WDC 65c02 running @ 2.68Mhz
- 44KB addressable RAM
- 8x0.5KB IO space
- 16KB ROM
- 2 x WDC 65c22 @ 2.68Mhz (used for software driven SPIO interface to SD Card, BBC keyboard interface, 8910 interface)
- CMD 6551 ACIA for serial IO
- TMS9918 VDP
- AY-3-8912 for sound and Atari compatible joystick interface
- All done on breadboard, then placed in a BBC micro case (sadly, had to junior hacksaw it to fit the breadboards!)

Now the focus is mainly software:
- Have built my own FAt16 routines for load, save, del of files on SDCard
- Serial input / output routines through a 6551
- Keyboard driver for BBC keyboard (full function, kind of)
- Screen driver routines (text only at the moment)
- Monitor software (memory dump, set, etc.)

The next software challenge now is to design and implement a ROM based interpreter, just like the home micros of the 80s (e.g. Oric, Atari, CBM, BBC).

Thanks again for the help to sort out my hardware issue - it was a silly error, but needed that independent set of expert eyes to spot!

Cheers, Dolo
https://hackaday.io/project/5789-6502-homebrew-computer

P.S. I did try and get this link added to the list of projects, but seemed to get a bounce from the webmaster..

Great project - thanks for the link. It would be good if you could also post major updates here on the forum!

Thanks BigEd. Yes will post significant updates of interest. I have three things that I am considering:
- ROM based interpreter. A lot of work and research but will be an interesting challenge
- Small game. Something simple but shows the various hardware in operation - VDP, joystick, sound
- Bank switching. Focus on RAM to use more of the 128K SRAM capacity.

I am sure I will be coming back for advice and tips!

Cheers, Dolo

Neat. I always admire the breadboard based designs. They're sort of like modeling clay that slowly gets sculpted into the desired form.

You're in the list now:
http://6502.org/homebuilt

Speaking of the homebrew page, the link to Samuel Falvo's Kestrel page is broken.

OK I've patched that up. For the record, his new site is here.
(This is of course off-topic... please start a new thread for a new discussion. Or just PM me, Mike or Garth for a site update.)

Hi BigEd - thank you very much. It feels kind of momentus to see my project on there with so many others that I have spent hours looking at to gaining knowledge and inspiration from! The thought that my project might make a small contribution to the next enthusiast taking up the 6502 is very gratifying.

Cheers, Dolo

Question for you Dolo from a nearby thread - how do you meet the timing for the 9918 video chip, which seems to want the CPU to stretch out accesses to 2us or even 8us?

(Related: have you any schematics or block diagram for your system? Any code, perhaps on github? The hackaday site seems to offer a project log and a gallery, but how does it work for documenting things so others can have a go at your project?)

Great answer from Dolo over here - thanks!

I too would like to see schematics and code, always something to learn from!

Hi chaps. Sorry didn't see the query from BigEd and Hans about more information etc. So the hackaday site is ok for putting together a blog and updates, although the ability to organise items for a reasonably complex project as this leaves much to be desired. Yes I am happy to put up my code on GitHub, will do that in the near future.

As for schematics, I do not have any! I do have various notes in Microsoft Word format, which I will also put up on GitHub. I hope that provides some insight and knowledge for people, but as always, please just ask for any more.

Cheers.

Great - even a block diagram is a win. If you have Word files, please also check in a pdf, or a readable link like
https://docs.google.com/viewer?url=http ... o/file.doc