ZX81 ULA-in-a-CPLD

Any discussions related to the creation of new hardware or software for the ZX80 or ZX81
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fordp2002
Posts: 1
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.

cheers
commie
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.

Zxkim81
Posts: 29
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: 811
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)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

McKlaud
Posts: 154
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.
Attachments
zULA81_prot_01.jpg
Claudius
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McKlaud
Posts: 154
Joined: Tue Dec 19, 2017 10:02 pm
Location: St Albans, UK

Re: ZX81 ULA-in-a-CPLD

Post by McKlaud » Fri Mar 09, 2018 1:46 am

Hi,

Still work in progress with porting the RetroTechie's implementation into XC9572XL, but small success achieved. The ULA mini board inside a real ZX81 hardware, the clock signals read from pin 6 of the CPU and the composite video output with a 75 Ohm load.
Attachments
zULA_video_out.png
video signal
zULA_Z80_3.25.png
CPU clock
zULA81_pro_03.jpg
zULA81
Claudius
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gammaray
Posts: 486
Joined: Sun Apr 17, 2016 2:44 am
Location: Texas

Re: ZX81 ULA-in-a-CPLD

Post by gammaray » Fri Mar 09, 2018 2:57 pm

Bravo!
Finish what you start. Truth is over the mountaintop or six feet under.
4 x TS1000, 2 x TS1500 , 2 x timex 2040 printer, 1/2 x timex 2020 cassette deck, ZXPAND+AY, ZeddyNET, ZXBlast..., unfinished Spectrum...Still no life!

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Andy Rea
Posts: 1490
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Location: notts UK

Re: ZX81 ULA-in-a-CPLD

Post by Andy Rea » Fri Mar 09, 2018 3:19 pm

Whooey, congratulations...
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum

Lardo Boffin
Posts: 811
Joined: Sat Nov 26, 2016 2:42 am

Re: ZX81 ULA-in-a-CPLD

Post by Lardo Boffin » Fri Mar 09, 2018 9:57 pm

Cool!
ZX81 iss 1 (bugged ROM, kludge fix, normal)
Iss 3 with ZXVid, another in nearly perfect box
TS 1000 iss 3, ZXPand AY, ZX8-CCB, ZX-KDLX & ChromaSCART
TS 1500
TS 2000
Spectrum 16k (iss 1 s/n 1499)
Various Spectrum 48ks plus a DIVMMC future and SPECTRA

User avatar
Andy Rea
Posts: 1490
Joined: Fri May 09, 2008 2:48 pm
Location: notts UK

Re: ZX81 ULA-in-a-CPLD

Post by Andy Rea » Fri Mar 09, 2018 10:40 pm

not to trying to put a damper on everyones projects, but i have also been tinkering away in the background and as they say small is beautiful...

2" x 0.7" so pretty much the same outline as the socket it fits into... NO Bells, No Whistles, No Gimmicks just a plain vanilla ULA plug in and go.

Image
Image
Image


of course some components on backside also
Last edited by Andy Rea on Sat Mar 10, 2018 12:12 am, edited 2 times in total.
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum

McKlaud
Posts: 154
Joined: Tue Dec 19, 2017 10:02 pm
Location: St Albans, UK

Re: ZX81 ULA-in-a-CPLD

Post by McKlaud » Fri Mar 09, 2018 11:54 pm

Andy, I am glad reading your post. :) You are Master Yoda of ZX81 ULA, I am just newbie in this world. BTW Could you correct pictures, I can't see them.
Claudius
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