ZX81 ULA-in-a-CPLD

Any discussions related to the creation of new hardware or software for the ZX80 or ZX81
Posts: 33
Joined: Mon Dec 23, 2013 5:33 pm
Location: United Kingdom

Re: ZX81 ULA-in-a-CPLD

Post by commie » Wed Dec 07, 2016 6:35 pm

Here is a good picture of chess that I loaded by tape....


and here is a better picture of hsync with some pixel data on it...


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Joined: Tue Aug 15, 2017 2:49 pm

Re: ZX81 ULA-in-a-CPLD

Post by fordp2002 » Tue Aug 15, 2017 2:53 pm

commie wrote:
Sat Nov 19, 2016 10:09 pm
I might just add that I'm using retrotechie's Xilinix implementation and ported it over to the Atmel atf1504 plcc44. Well, I'm at a loss as to why it wont work in slow mode? Everything else including the tape load/save works perfectly, but only in fast mode.

Did you get anywhere with your ATF1504 design. If you have I am interested in making a ZX81 PCB for it ;) I could send you one if I get it done.

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Joined: Sat Mar 18, 2017 7:44 pm

Re: ZX81 ULA-in-a-CPLD

Post by Zxkim81 » Sun Dec 24, 2017 5:44 pm

This replacement ula will save the zx81 your work is brilliant 😁
Someone has to follow up on your work with the view of marketing this replacement ula.

Lardo Boffin
Posts: 701
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX81 ULA-in-a-CPLD

Post by Lardo Boffin » Sun Dec 24, 2017 8:50 pm

I would certainly be in the market for several!
ZX81 iss 1 (bugged ROM, kludge fix, normal, kit)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB & ZX-KDLX
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Spectrum 48k
Toastrack + DIVMMC future

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Joined: Tue Dec 19, 2017 10:02 pm
Location: St Albans, UK

Re: ZX81 ULA-in-a-CPLD

Post by McKlaud » Tue Jan 23, 2018 9:48 pm

Unfortunately all pictures stored on PhotoBucket gone and no chance to see what was on them. :(

Anyway, one of my ZX81s is dead and I decided to recreate the RetroTechie's implementation using XC9572XL. The prototype PCB on a breadboard under 13MHz generator test is in full flesh on the attached photo.

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