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ZX81 Mechanical Keyboard

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Re: ZX81 Mechanical Keyboard

#41

Post by bemusedthrow75 »

RachelF wrote: post #36
swetland wrote: post #33

Earlier quoted context omitted.

It's replicating the ZX81 keyboard, including all the quirks except for the horrific membrane keys. https://upload.wikimedia.org/wikipedia/commons/8/8a/Sinclair...

keys which Microsoft decided to bring back in their original Surface line.

Not the same! :-) The ZX81 keyboard really was objectively difficult, even for the time.

In terms of their feel, the MS keys (and e.g. the iPad Keyboard Cover keys) are rather more like the (still IMO wonderful, and pioneering) keys of the Cambridge Computers Z88 (also a Clive Sinclair product). Raised keycaps with a larger volume of air to move the membrane. Quiet and mostly usable at a reasonable pace.

The ZX80/81 membrane keyboard was entirely flat except for the tiniest hint of membrane bubble, with a uniform textured matt finish. Not even textured outlines around the keys. Surprisingly robust; maybe more so than the membrane keyboard of the Atari 400 (which is also a classic of visual design), or, say, that of the BigTrak.

Re: ZX81 Mechanical Keyboard

#42

Post by benj111 »

Why was this never a thing back in the day? I can see the wisdom of getting a cheap one out of the door, but certainly by the time you've got the spectrum, it seems a no brainer to release one with a nice keyboard.

I know Sinclair later released computers with nicer keyboards, but it wasn't just a straight speccy.

Re: ZX81 Mechanical Keyboard

#43

Post by rwmj »

realjhol wrote: post #20

I always wondered, what do the black and white square icons mean?

In addition to other answers, ZX81 BASIC had a PLOT command to draw a "dot" on the screen. However since the display was character based (32x24 grid, but the bottom two lines are reserved) what this command actually did was place one of 16 2x2 black and white blocks at the particular character location (giving 64x44 resolution). If there was already a non-block character at the location it was replaced. (Also UNPLOT which was the same except drawing a white quarter-pixel). There were no line or circle drawing commands, so you had to implement that yourself.

Here's the manual reference:

https://worldofspectrum.net/ZX81BasicProgramming/chap18.html

Recently Unicode added these characters:

https://en.wikipedia.org/wiki/Symbols_for_Legacy_Computing

Re: ZX81 Mechanical Keyboard

#44

Post by rwmj »

benj111 wrote: post #42

Why was this never a thing back in the day? I can see the wisdom of getting a cheap one out of the door, but certainly by the time you've got the spectrum, it seems a no brainer to release one with a nice keyboard. I know Sinclair later released computers with nicer keyboards, but it wasn't just a straight speccy.

Because the computer was built to a price and there's no way they could have included a proper keyboard for that price. The ZX81 kit was £49.95 (£204 today) or £69.95 assembled (£285 today). Note that 15% of the price was tax, and if sold through retail probably half went to the shop.

(I'd love to see a full 1981 BOM for the ZX81, but finding old prices of components is tricky)

Re: ZX81 Mechanical Keyboard

#45

Post by benj111 »

rwmj wrote: post #44
benj111 wrote: post #42

Why was this never a thing back in the day? I can see the wisdom of getting a cheap one out of the door, but certainly by the time you've got the spectrum, it seems a no brainer to release one with a nice keyboard. I know Sinclair later released computers with nicer keyboards, but it wasn't just a straight speccy.

Because the computer was built to a price and there's no way they could have included a proper keyboard for that price. The ZX81 kit was £49.95 (£204 today) or £69.95 assembled (£285 today). Note that 15% of the price was tax, and if sold through retail probably half went to the shop. (I'd love to see a full 1981 BOM for the ZX81, but finding old prices of components is tricky)

No I get that. But once you get to a certain point an ecosystem develops where you have small game Devs who would probably want a nicer computer, you have the small business owner / parent who learnt to use the computer, has a bit more to spend, has a legitimate use and is willing to spend a bit more.

Even if the price quadrupled if someones relying on that hardware, and the keyboard makes their job easier, it seems it would sell.

Plus, compared to the 90s £285 is cheap. I wish my computer's were that cheap back then. My first computer was over £500 (so what £1000 today?) and it wasn't top of the line, and I had to put it together myself.

Re: ZX81 Mechanical Keyboard

#46

Post by fifticon »

benj111 wrote: post #42

Why was this never a thing back in the day? I can see the wisdom of getting a cheap one out of the door, but certainly by the time you've got the spectrum, it seems a no brainer to release one with a nice keyboard. I know Sinclair later released computers with nicer keyboards, but it wasn't just a straight speccy.

it was, my father made a cherry mx kbd for ours, based on a magazine article

Re: ZX81 Mechanical Keyboard

#47

Post by shever73 »

bemusedthrow75 wrote: post #40
shever73 wrote: post #38

Earlier quoted context omitted.

Typing on a ZX family machine was different. The keys look busy because you didn’t type out the keywords like you did on most other machines. Instead, a variety of keyboard modes inserted them - along with the required spaces - for you. To load a program from tape on a ZX Spectrum you simply pressed J, which would insert the keyword LOAD along with a trailing space, and then hold Symbol Shift and press P twice to get…

Right -- and there is a hugely important consequence of this design for people learning to program: It was almost impossible to enter a syntactically incorrect program. Because the keyboard routines were doing the work of what would now be a lexer and parser. The keyboard would only let you enter syntactically valid code. One other nostalgia side-effect; where many games for eight bit computers used Q-A-O-P- for dire…

Yes, there were occasional instances of "C Nonsense in BASIC" errors, but that was for very specific cases. Mostly, the cursor would change to a flashing question mark if you tried to enter something syntactically incorrect.

Re: ZX81 Mechanical Keyboard

#49

Post by AvocadosNombre »

nickcw wrote: post #11

That is a sweet keyboard. It is rather better than my homemade one from 1982 https://twitter.com/njcw/status/1368566103933337603 My dad gave me a old keyboard from something and I traced the zx81 PCB to discover how it was wired, then rewired the new keyboard the same. I connected it by burning a hole in the case with my soldering iron to poke the wires through! It was a dream compared to the membrane keyboard.

Unrelated, but I thought I recognized that username, thanks for making rclone!

Re: ZX81 Mechanical Keyboard

#50

Post by soegaard »

qiqitori wrote: post #23
nickcw wrote: post #11

That is a sweet keyboard. It is rather better than my homemade one from 1982 https://twitter.com/njcw/status/1368566103933337603 My dad gave me a old keyboard from something and I traced the zx81 PCB to discover how it was wired, then rewired the new keyboard the same. I connected it by burning a hole in the case with my soldering iron to poke the wires through! It was a dream compared to the membrane keyboard.

Were you able to diagnose what's wrong with your ZX81? Usually it's a simple problem, it just takes a while to diagnose. BTW, if you do want to get rid of it at some point, it would be nice if you could sell it on ebay or locally. The number of ZX81s left will just keep going down and they are quite decent for learning about electronics/digital systems.

It was not unseen to replace the original "keyboard" with mechanical one back then. The membrane keys were awful.
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