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ZX81 ULA
Posted: Wed Jun 27, 2018 11:12 pm
by Andy Rea
as some of you may be aware i have developed and built another ZX81 ULA based this time around Xilinx CPLD.
Designed to give composite video output will drive 75ohm or hi-z inputs
( can be made to drive the UM1233 modulator
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.
Re: ZX81 ULA
Posted: Thu Jun 28, 2018 7:43 am
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
Re: ZX81 ULA
Posted: Thu Jun 28, 2018 7:59 am
by mrtinb
And thank you too.
Re: ZX81 ULA
Posted: Thu Jun 28, 2018 11:07 am
by 1024MAK
Thanks Andy
I grabbed the last one in that batch about half an hour before midnight, so yes they did sell fast...
Mark
Re: ZX81 ULA
Posted: Thu Jun 28, 2018 11:37 am
by Andy Rea
1024MAK wrote: ↑Thu Jun 28, 2018 11:07 am
Thanks Andy
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
Re: ZX81 ULA
Posted: Thu Jun 28, 2018 11:56 am
by 1024MAK
Yeah, no problem.
Mark
Re: ZX81 ULA
Posted: Thu Jun 28, 2018 6:53 pm
by Floopy
I was just looking for a replacement and it went by too fast. They are not overly expensive also!
Re: ZX81 ULA
Posted: Thu Jun 28, 2018 6:58 pm
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.
Re: ZX81 ULA
Posted: Thu Jun 28, 2018 8:39 pm
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
Re: ZX81 ULA
Posted: Fri Jun 29, 2018 10:39 pm
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.
Great work as always Andy many thanks for this.
Moggy.