ZX81 ULA
ZX81 ULA
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.
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.
Last edited by Andy Rea on Fri Jun 29, 2018 11:42 pm, edited 2 times in total.
what's that Smell.... smells like fresh flux and solder fumes...
Re: ZX81 ULA
Well they went fast! Will be building more this weekend so check back Monday.
Thank you to those that were quick enough.
Regards Andy
Thank you to those that were quick enough.
Regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
Re: ZX81 ULA
And thank you too.
- 1024MAK
- Posts: 5165
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: ZX81 ULA
Thanks Andy
I grabbed the last one in that batch about half an hour before midnight, so yes they did sell fast...
Mark
I grabbed the last one in that batch about half an hour before midnight, so yes they did sell fast...
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
Re: ZX81 ULA
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
what's that Smell.... smells like fresh flux and solder fumes...
- 1024MAK
- Posts: 5165
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: ZX81 ULA
Yeah, no problem.
Mark
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer being good this year.
Re: ZX81 ULA
I was just looking for a replacement and it went by too fast. They are not overly expensive also!
-Floopy
Re: ZX81 ULA
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
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
what's that Smell.... smells like fresh flux and solder fumes...
Re: ZX81 ULA
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.
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.