ZX81 External Keyboard
ZX81 External Keyboard
If I wanted to make or repurpose a keyboard to use with a ZX81, is it safe to use the A8..15 Lines and the 5v connections on the edge connector? I know I'd need the pull-up resisters and the diodes, but would it be safe to do so? It would be nice to have an external keyboard which plugs into the back, but I prefer to have a working ZX81!
Cheers.
Cheers.
2x ZX81 / 2xZ88 / Spectrum 48K / Spectrum+ / Spectrum +2 (Grey) / Spectrum +3
Harlequin Rev G
Harlequin Rev G
Re: ZX81 External Keyboard
I used Wilf Rigter's schematic to create my own external keyboard controller. I'm sold out of the pcbs I made. It was my first electronics project, so anyone should be able to do it.
Last edited by mrtinb on Sat Sep 08, 2018 6:35 pm, edited 1 time in total.
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Re: ZX81 External Keyboard
Yes, if using the edge-connector, as a minimum, you need a tri-state buffer (a chip where it's output pins can be switched to be open circuit) and some minimal control and address decoding to control the keyboard data going to the data bus.
Mark
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer 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 later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer 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 later in the year.
Re: ZX81 External Keyboard
Thanks for the replies. Looks like it would be a bit too complex for my abilities. Maybe I should just keep looking out for a Memotech keyboard or something similar on ebay. I imagine they are as rare as hens teeth.
Becky.
Becky.
2x ZX81 / 2xZ88 / Spectrum 48K / Spectrum+ / Spectrum +2 (Grey) / Spectrum +3
Harlequin Rev G
Harlequin Rev G
Re: ZX81 External Keyboard
The German forum has designed a new controller and new keyboard with cherry keys with ZX81 symbols. It might be a product to buy soon.
Edit: Link to keyboard in German forum
Edit: Link to keyboard in German forum
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Re: ZX81 External Keyboard
Ooh. That looks nice!
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 External Keyboard
Indeed!
- 1024MAK
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- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: ZX81 External Keyboard
It is possible to solder wires to the existing keyboard connector solder terminals on the underside of the Zeddy board. No need to disturb the existing keyboard or it's membrane.
That way, no electronic components are needed (apart from the switches of course ).
If you use coloured ribbon cable, you can fit it through the expansion port. Although it may get very tight for space if you have an expansion plugged in.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer 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 later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer 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 later in the year.
Re: ZX81 External Keyboard
are they for sale anywhere ?mrtinb wrote: ↑Sat Sep 08, 2018 3:22 pm The German forum has designed a new controller and new keyboard with cherry keys with ZX81 symbols. It might be a product to buy soon.
Edit: Link to keyboard in German forum
regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
Re: ZX81 External Keyboard
They will be most probably for sale in Mahlerts 2019. Are you and Sirmorris coming?
In theory, there is no difference between theory and practice. But, in practice, there is.