ZX81 ULA

ZX80 / ZX81 hardware and software offered for sale or swapping
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Andy Rea
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ZX81 ULA

Post by Andy Rea »

as some of you may be aware i have developed and built another ZX81 ULA based this time around Xilinx CPLD.
Image

Designed to give composite video output will drive 75ohm or hi-z inputs
( can be made to drive the UM1233 modulator :roll: with an extra 1K resistor )

On board crystal oscillator for improved frequency control.

Pre amp to assist in tape loading, works excellent with OTLA https://code.google.com/archive/p/otla/downloads

M1not can be enabled easily.

anyway... words are not my thing... simple guide here.

SellMy Retro Link

Regards Andy

P.s more will be listed soon, so dont worry if you dont get one this time.
Last edited by Andy Rea on Fri Jun 29, 2018 11:42 pm, edited 2 times in total.
AFK
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Andy Rea
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Re: ZX81 ULA

Post by Andy Rea »

Well they went fast! Will be building more this weekend so check back Monday.

Thank you to those that were quick enough.

Regards Andy
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mrtinb
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Re: ZX81 ULA

Post by mrtinb »

And thank you too.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
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1024MAK
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Re: ZX81 ULA

Post by 1024MAK »

Thanks Andy 8-)

I grabbed the last one in that batch about half an hour before midnight, so yes they did sell fast...

Mark
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Andy Rea
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Re: ZX81 ULA

Post by Andy Rea »

1024MAK wrote: Thu Jun 28, 2018 11:07 am Thanks Andy 8-)

I grabbed the last one in that batch about half an hour before midnight, so yes they did sell fast...

Mark
I was most surprised by the first buyer... The link had not even been posted here at that point.... However it was late so I went to bed. When I woke this morning it's time for work so I will be packing today and posting tomorrow. Hope this is acceptable.

Regards Andy
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1024MAK
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Re: ZX81 ULA

Post by 1024MAK »

Yeah, no problem.

Mark
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Floopy
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Re: ZX81 ULA

Post by Floopy »

I was just looking for a replacement and it went by too fast. They are not overly expensive also!
-Floopy
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mrtinb
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Re: ZX81 ULA

Post by mrtinb »

We haven’t got a replacement ULA for years, so you came at the right time. Wait a week and there will be more.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
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Andy Rea
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Re: ZX81 ULA

Post by Andy Rea »

Floopy wrote: Thu Jun 28, 2018 6:53 pm I was just looking for a replacement and it went by too fast. They are not overly expensive also!
Hi will be making more over the weekend, keep your eyes peeled late Sunday night or Monday morning, I'll post here again when re listed.

Regards Andy
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Moggy
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Re: ZX81 ULA

Post by Moggy »

Fitted-running-working.

A nice piece of work Andy that takes care of the only worrisome bit of the zeddy, the ULA.

Z80's, caps, resistors and even a quick flash job for the ROM no worries but this bloody thing was always at the back of my mind insomuch as when my last ULA's hit the dirt what then? Hopefully now problem solved. :D

Great work as always Andy many thanks for this.


Moggy.
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