🇬🇧 Cambridge Computer Z88: Part 3 (Mechanical Keyboard Test) [TCE #0626]
40Thanks to #PCBWay for their ongoing support! https://www.pcbway.com/
The rubber mat on my Z88 doesn't work very well so let's try replacing it with a mechanical keyboard.
I've designed this keyboard to use Gateron KS-33 low profile switches and, after a lot of searching, settled on a set of MA profile key caps that included an ISO ENTER key:
Aliexpress store name: Skyloong Guangming Store
Aliexpress store ID: 910796037
https://www.aliexpress.com/item/1005004649108572.html
I still need to find a few more spare key caps for the special keys.
MA profile are taller than XDA or DSA profile ... DSA profile might be the best but it's just a matter of trying to find a complete set in black ...
The keyboard is working fine from my initial testing.
I didn't allow for a few millimetres of overhang by the LCD bezel, so I need to shave this off the top of my PCB to allow everything to fit back together nicely ... that'll be REV. B.
My Github repository:
https://github.com/0ddjob/Sinclair/tree/main/Z88_Mechanical_Keyboard
00:00 ... Intro
03:15 ... The PCB
05:50 ... Soldering Tunes
06:45 ... Testing the first row
12:07 ... Full keyboard ready for testing
13:59 ... Comparison with original rubber mat
15:13 ... Testing with BASIC
18:49 ... Adjustments required
21:12 ... Channel thanks & outro
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From Part 2:
The Universal Backpack Drive (uBPD) can be used on the Z88! I almost got it working before the damn rubber keyboard stopped working.
You'll need a converter for the Z88's serial board - a few options are available. I designed my own as I didn't order one with the uBPD, and it was the cheapest & fastest option for me:
https://github.com/0ddjob/Sinclair/tree/main/Z88_Serial_DE9-to-DB25
You'll need a disk manager program on the Z88, perhaps transferred via serial cable using PC Link or Mac Link software. Luckily I happened to have an EPROM with it installed.
Unfortunately then the keyboard stopped working before I could continue. Sorry but the keyboard on my Z88 seems to be rubbish. I want to see if I can design a replacement so I can make my Z88 actually usable ... okay, maybe there is still something I could do to improve the rubber keyboard ... ?
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From Part 1:
What Sir Clive did next. I've always been interested in this machine - a Zilog Z80 based, notepad sized computer with BBC BASIC and a decent screen. Not too sure about the rubber keyboard. But ... the machine does live on with various upgrades available.
WoS info:
https://worldofspectrum.org/z88forever/index.html
Z88 motherboard mods:
https://privat.bahnhof.se/wb782177/z88/motherboard.htm
Z88 Wiki:
https://cambridgez88.jira.com/wiki
ROM replacement:
https://github.com/bkw777/aDIPters
Z88 parts:
http://www.rakewell.com/main/index.shtml
Universal Backpack Drive:
https://www.soigeneris.com/universal-backpack-drive
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Music by Karl Casey @ White Bat Audio
https://karlcasey.bandcamp.com/
/ @whitebataudio