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Re: zx spectrum in zx81 case

Posted: Mon Jan 08, 2018 11:56 pm
by McKlaud
rune wrote:
Sat Jan 06, 2018 3:27 pm
Nope still the same log. The CPLD is warm. I've checked continuity from the 10 pin header to CPLD and all is good. Voltage to the board is good.
To be honest I bought five (5) CPLD chips from a Far East supplier and only 2 are fine. Anyway, good luck with your board.

@superfo designed an interface to the Issue 1. The interface is a combination of the Kempston type joystick port and the IF2 cartridge slot. It works with any ZX Spectrum and is compact and very handy. See below.

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And the last but not least, below is a teaser about the Issue 2 board. This PCB is still hot and arrived to me a few days ago.

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Re: zx spectrum in zx81 case

Posted: Tue Jan 09, 2018 5:32 pm
by gammaray
nollkolltroll wrote:
Tue Nov 21, 2017 6:30 am
Interesting choice of travel...
Since there is a CPLD or FPGA sitting there, it would presumably be possible to create a ZX80/81/Spectrum switchable in the same case?
Interesting and worthy concept, I wish I knew how!

There would have to be a change in bus layout. Maybe a driver/buffer board to switch signals?

There would have to be a keyboard overlay. Larger ROM for both monitors (Op Sys)

And other things without being an emulator... May be too complicated to implement electrical layout.

Re: zx spectrum in zx81 case

Posted: Wed Jan 17, 2018 4:16 pm
by McKlaud
Newer version of the ZX Max is alive.

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I have got two spare PCBs (one white and one blue). If anyone is interested in them, please feel free and send me a PM. Only one rule applies: "First come, first served."

Re: zx spectrum in zx81 case

Posted: Wed Jan 17, 2018 10:39 pm
by McKlaud
All gone :) Lucky guys are: Paul & 1024MAK :)

Re: zx spectrum in zx81 case

Posted: Thu Jan 18, 2018 2:19 pm
by msch
Beautifull! I really like the yellow/amber PCB...

Re: zx spectrum in zx81 case

Posted: Sat Jan 20, 2018 6:33 pm
by rune
A bit more info on my build.

Dont buy the IC "packs" from ebay. I got some new CPLDs from elsewhere the first out the packet programmed immediately. Then the Eprom wasnt recognised in either of my programmers. Another eprom programmed fine.

Next the test - lots of coloured squares and the Z80 getting warm. I've tried swapping the RAM, using one at a time and even a new one. It didnt help.

Tomorrow I'll get the CPU swapped out and try some diagnostics on the scope, but those "project" kits seem to be utter rubbish.