Sinclair ZX80 / ZX81 / Z88 Forums

Hello everyone,

I'm Olivier, 51 years old, and I live in France. I am a big Amstrad enthusiast and I own two CPC 6128s with several dozen interfaces, and several hundred games and utilities. I also program in Basic (and Z80 but that was a long time ago).

When the ZX81 came out I was 8 years old, and I still remember it very well. My Dad almost bought one.

And now I have just acquired one in 2024. I'm really happy to own it, for me it's really the precursor of family computing at the very beginning of the 80s

This is a version with the mechanical keyboard :


I also have the complete instructions in French, a 16 KB memory extension, an R.G.B. extension :


I also bought a ZXpand+ extension in order to take advantage of the SD support (and 32 KB memory + joystick port + reset button + AY-3-8910 sound) :


I can't wait to discover games and utilities.

My next step is to modify the UHF video output to have a higher quality Composite output.

I wish you success with the AV conversion.
Please make sure which Modulator and video circuit you have.
There are UK US and French models as well.
Please compare with the circuit diagram.

My ZX81 is a French model.
I have bought this ZX81 Composite Video : https://www.ebay.fr/itm/255073144065

poulette73 wrote: ↑Wed Feb 21, 2024 5:09 pm Hello everyone,

I'm Olivier, 51 years old, and I live in France.

Welcome.

I also bought a ZXPand+ extension in order to take advantage of the SD support

I can't wait to discover games and utilities.

lucky you, not everyone can get a zxpand.
As for games.... you can try my 1K hires games (and 1k lowres and 16k lowres and 16k hires). Available in the new games section.

Thank you for the welcoming.
I'm going to take a look in the games section.

For the ZXpand+, there are still on sale : https://www.sellmyretro.com/offer/detai ... pand-63279

Hello and welcome to our forum Olivier!



I hope you enjoy this forum

You are welcome to ask questions!

With respect to the modulator / video circuitry, it's recommended to take the video feed for the composite video board from pin 16 of the ULA from the underside of the board. If removing the modulator, also carefully remove any components (transistor) connected to it.

Mark

Hello,

And thank you for the valuable advice.
Do you have a photo of the underside card to locate pin 16 of the ULA ?

I can take one and post it up later today.

Mark

Issue one board Issue 3 board Click on the pictures for the full size version.

Pin 16 shown. An alternative is on the connection for diode D9 indicated.

Mark

Thank you for these photos, and for taking the time !
This is really nice.

So what I understood : the best is to connect as a priority to pin 16 in order to obtain the best possible result (diode D9 is a second alternative).
I am waiting to receive my kit, and I will comment on my result here after modification.