I tried to make a schematic and footprint symbol for the R6501 using kicad. If you use it you will have to check it's OK because I gave up trying to use that dreadful software. I'm going to try geda or orcad386.

I'd like to thank everyone for their help and interest.
The disassembler looks nice with the labels (Thanks White Flame).

It makes sense that it enters a loop. It's waiting for two things, either a command from the Atari software which makes the R6501 output SMPTE timcode, or a SMPTE timecode ...

Did the site have a little meltdown then? I couldn't post.

Hi Garth,
If you mean starting at D7BD as in loading the code from that location then It doesn't disassemble anything. I think because there's an $02 in the way?
Sorry about the formatting, it wasn't the disassembler's fault, honest.

If it ...

Hi Arne,

Yes A15 goes through a 7404 and the output of that goes to OE.

Thanks
Martin

Hi Arne,

I stuck that 27C256 in there so it would use less power than the 27128 that was in there before. I didn't have a spare cmos 128. They are more expensive than a C256. The original was a 128.
All the eprom data pins correspond to the correct R6501 pins and addresses A12..0 are correct and ...

Thanks everyone for showing some interest.

I'm off to read some datasheets now and will probably need to draw a proper schematic up to help me
Welcome, martin8or, and good luck with your project. Um... What exactly is your project?!! :?: :?: :)

I ask simply out of curiosity. But I would be interested in more details. A description, maybe ...

If I go to the last 6 bytes at 3ffa..3fff
I see
7f d0 bd d7 4a d0
If I use the R6501 settings in the disassembler I get

3fba: L3fba brk
3fbb: 00 00 00 00 00
3fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
3fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
3fe0: 00 00 00 00 00 00 00 00 ...

^ I did try your disassembler yesterday but it didn't work because I hadn't named the file to .bin. it works now.
Thank you Arne and White Flame.

I don't know what the load address is so I just used 0000.
I think my binary might be able to work with 2 different processors. The first bytes are 02 85 ...

Hi all,
I'm a complete beginner.

Any pointers on what to use as a disassembler for R6501?
I tried an online one for 6502 but there were a few too many ???. I would like to minimise as much head scratching as possible.

Thanks
Martin