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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Andy Rea
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Re: ZX81 ULA-in-a-CPLD

Post by Andy Rea »

McKlaud wrote: 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.
see if it images show now

regards
what's that Smell.... smells like fresh flux and solder fumes...
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1024MAK
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Re: ZX81 ULA-in-a-CPLD

Post by 1024MAK »

Images now showing for me :ugeek:

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
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Re: ZX81 ULA-in-a-CPLD

Post by McKlaud »

Andy Rea wrote: Sat Mar 10, 2018 12:13 am
McKlaud wrote: 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.
see if it images show now

regards
Thanks a lot, now they are perfectly visible :)
Claudius
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gammaray
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Re: ZX81 ULA-in-a-CPLD

Post by gammaray »

Estimated power usage...really low?
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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Re: ZX81 ULA-in-a-CPLD

Post by McKlaud »

In my case the CPLD is not even warm. The hottest part in my testing board is the ROM chip now. The power consumption is roughly 250mA, but I have also got a 16KB SRAM chip on this board. I think I could go even lower if the 7805 were replaced with any decent DC-DC converter.
Last edited by McKlaud on Sat Mar 10, 2018 1:02 am, edited 1 time in total.
Claudius
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gammaray
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Re: ZX81 ULA-in-a-CPLD

Post by gammaray »

:P :D :shock: ;)
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
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Re: ZX81 ULA-in-a-CPLD

Post by McKlaud »

First "K" seen on the screen, but some issues with stability and timings.
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zULA_prot_04.jpg
Claudius
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RetroTechie
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Re: ZX81 ULA-in-a-CPLD

Post by RetroTechie »

@McKlaud and Andy: NICE!!! :) Especially Andy's 45-degree placement of the CPLD is likely how I'd have done it myself.
McKlaud wrote:The power consumption is roughly 250mA, but I have also got a 16KB SRAM chip on this board. I think I could go even lower if the 7805 were replaced with any decent DC-DC converter.
Indeed. My ZX81 pulls around 800 mW, that is DC-DC converter included. Some 600 mW (120 mA @5V) if powered with 5V directly. CMOS Z80 and CPLD macrocells in low-power mode are the biggest quick/easy savings afaik.
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Andy Rea
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Re: ZX81 ULA-in-a-CPLD

Post by Andy Rea »

Top job Claudius, it's a very rewarding feeling when you get an image for the first time.

@retrotechie, cheers man, the driving factors for that kind of placement was size wanted it basically the same size as the socket and i really wanted all 40 pins through hole instead of the central ones been smd It does mean that i lose 4 pins as the corner ones are so close to the through holes that they are doubled up. But plenty of pins anyway.

Regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
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Re: ZX81 ULA-in-a-CPLD

Post by Moggy »

Well done to all concerned.

Look forward to seeing these on Sell My Retro. :D
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