ZX80 3K Ram Pack memory

Discussions about Sinclair ZX80 and ZX81 Hardware
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1024MAK
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Re: ZX80 3K Ram Pack memory

Post by 1024MAK » Fri Apr 13, 2018 8:48 pm

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

Mark

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mhudson52
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Re: ZX80 3K Ram Pack memory

Post by mhudson52 » Fri Apr 13, 2018 9:12 pm

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

Mike
TS 1000 bought in 1982 and brought back to life by Sir Ian

sirmorris
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Re: ZX80 3K Ram Pack memory

Post by sirmorris » Fri Apr 13, 2018 11:59 pm

Oh.
:oops:

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1024MAK
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Re: ZX80 3K Ram Pack memory

Post by 1024MAK » Sat Apr 14, 2018 1:24 am

mhudson52 wrote:
Fri Apr 13, 2018 9:12 pm
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 :roll:

Mark

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Re: ZX80 3K Ram Pack memory

Post by 1024MAK » Sat Apr 14, 2018 1:44 am

Using this program:
IMG_6765.JPG
RAMTOP Program
I get these results on a standard ZX81:
IMG_6766.JPG
Results on a 1k ZX81
Mark

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Re: ZX80 3K Ram Pack memory

Post by mhudson52 » Sat Apr 14, 2018 2:31 am

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

BTW, Charlie, that was a most impressive solution! :D
TS 1000 bought in 1982 and brought back to life by Sir Ian

sirmorris
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Re: ZX80 3K Ram Pack memory

Post by sirmorris » Sat Apr 14, 2018 1:20 pm

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.

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Re: ZX80 3K Ram Pack memory

Post by 1024MAK » Sat Apr 14, 2018 1:27 pm

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

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Re: ZX80 3K Ram Pack memory

Post by mhudson52 » Sat Apr 14, 2018 2:34 pm

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
TS 1000 bought in 1982 and brought back to life by Sir Ian

sirmorris
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Re: ZX80 3K Ram Pack memory

Post by sirmorris » Sat Apr 14, 2018 3:02 pm

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

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