ZX80 3K Ram Pack memory

[1024MAK]

Mike, can you clarify, are you trying to test your 3k RAM pack on a ZX80 or a TS1000?

Mark

[mhudson52]

Mark, trying to test on a TS1000. Don't have any other machines available.

Mike

[sirmorris]

Oh.

[1024MAK]

Mark, trying to test on a TS1000. Don't have any other machines available.

Mike

Apart from the different TV timing (and reduction in slow mode processing speed), it should be same as a ZX81. So the same program should work. It's too late here for my brain to spot the problem

Mark

[1024MAK]

Using this program:

RAMTOP Program

I get these results on a standard ZX81:

Results on a 1k ZX81

Mark

[mhudson52]

Thanks, Mark, I'll give it a go a report back the results.

BTW, Charlie, that was a most impressive solution!

[sirmorris]

Thanks Mike. I have now run the ZX80 mem approximator on a real ZX80 with the pack and I get ... (drum roll please)

20468!

20468 - 16384 = 4084

Which is very nearly 4k.

1K internal + 3K?

So I think it's working.

[1024MAK]

Yes, the "3k" RAM pack actually contains 3k bytes of RAM. The decoding circuit also maps the internal 1k bytes of RAM so with a ZX80 or ZX81 you should get a total of 4K bytes.

Mark

[mhudson52]

I wasn't aware that it would piggy-back itself to the existing memory and yield 4K total memory. Not having either a ZX80 or 81 to test on is a handicap for me.

I may just have to purchase the Bulgarian ZX80 clone kit and stick it in my 3D printed case with decals to have a new addition to my shelf. My vacuum molded case isn't quite ready for prime time.

Awesome work, guys, and thanks!

Mike

[sirmorris]

You're most welcome. I'm happy to expend energy in favour of those who themselves contribute.