Zx81 composite mod with backporch-Advice
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- Posts: 2191
- Joined: Sat Nov 26, 2016 2:42 am
Re: Zx81 composite mod with backporch-Advice
It kind of looks like it is trying to produce a K at the bottom of the screen so may just be down to the adjustments?
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: Zx81 composite mod with backporch-Advice
I should learn to count!
I it works how attached to the correct pin on the ULA. The strange things is I count the pins, checked with the multi-meter it was the right pin, and then solder to the next pin down!
I it works how attached to the correct pin on the ULA. The strange things is I count the pins, checked with the multi-meter it was the right pin, and then solder to the next pin down!
Last edited by 1024MAK on Sun Feb 05, 2023 8:22 pm, edited 1 time in total.
Reason: Edited by a moderator to remove unneeded quote tags (user quoted themselves instead of editing)
Reason: Edited by a moderator to remove unneeded quote tags (user quoted themselves instead of editing)
ZX81 (purchased November 1982), my first computer.
ZXpand+, ZX8-CCB.
ZXpand+, ZX8-CCB.
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- Posts: 2191
- Joined: Sat Nov 26, 2016 2:42 am
Re: Zx81 composite mod with backporch-Advice
Oh yes! Pin 17 not 16. Easily done.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: Zx81 composite mod with backporch-Advice
A working ZX81!!!
And the modern equipement:
Thought I had a problem with the keyboard, but I hadn't push one connector in far enough.And the modern equipement:
ZX81 (purchased November 1982), my first computer.
ZXpand+, ZX8-CCB.
ZXpand+, ZX8-CCB.
- 1024MAK
- Posts: 5165
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Zx81 composite mod with backporch-Advice
I’ve got a very similar analogue multimeter:
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 composite mod with backporch-Advice
Me too as a reminder of the AVO units I used as an apprentice many years ago!
Re: Zx81 composite mod with backporch-Advice
I remember this one (or similar) from college.
ZX81 (purchased November 1982), my first computer.
ZXpand+, ZX8-CCB.
ZXpand+, ZX8-CCB.
Re: Zx81 composite mod with backporch-Advice
After spending half an hour trying out the ZXpand+ I got recently, and playing games like 3D Monster Maze, I will invest in one. I was a bit unnerved when the screen blanks to build the maze, and saw the message no signal. I had fogotten about FAST mode. When this happened back in the 80's with my little B&W TV it didn't bother me at all, e.g. no on screen message about no signal.Lardo Boffin wrote: ↑Thu Jan 05, 2023 11:34 am I would also get a KDLX keyboard at the same time. Much better than a standard flat membrane.
ZX81 (purchased November 1982), my first computer.
ZXpand+, ZX8-CCB.
ZXpand+, ZX8-CCB.