Sinclair ZX80 / ZX81 / Z88 Forums

1024MAK wrote: ↑Tue Aug 25, 2020 6:02 pm Looks good

<Slinks away to go and shake the piggy bank to see what level the funds are at...>

So if you do sell some boards, I would definitely be interested in buying one

The existing keyboard on mine is okay for occasional use, but does my head in if I actually try to code using it

Oh, and do tell use about which keycaps you went for...

Mark

Hi Mark,

I have 2 boards left, happy to send you one. Please PM me and we can sort out the details.


I went for a pack of Blank Black Filco 104 Key Keyset:
https://www.kustompcs.co.uk/peripherals ... s-layout/

I printed the key labels of printable vinyl:
https://www.amazon.co.uk/PPD-Inkjet-Adh ... _td_asin_2

Instead of fixer spray I went for a sheet of clear vinyl on top:
https://www.ebay.co.uk/itm/Vinyl-Rolls- ... 8c4ae6cb7

Finally I ran this key layout through our Silhouette cutting machine to cut out the keys:
Hope that helps

Thanks for those that have taken Ace keyboard PCBs from me; I hope you have fun putting them together.

I'd love to see some pics of them in action.

Here is how mine finally went together in my case. Boy what a difference it makes to have a real keyboard on the machine

Now the internal connectors are taken out to the back panel, I aim to create a bus extender so that I can add internal upgrades, and/or make the expansion connector available for external upgrades.

Question: Does anyone happen to have a KiCAD model of the external edge connector for the Ace I can use? If not I will create my own.



Many thanks in advance

Question: Does anyone happen to have a KiCAD model of the external edge connector for the Ace I can use? If not I will create my own.

I knocked these up this evening with a view to connecting them via a 50 way IDC connector.

Connecting into the back of the Ace to a ribbon cable -- I have a ZX81 edge connector that I plan to modify to solder onto the tabs:
Connecting from the ribbon cable to the back of the case with holes for PCB mounts for bottom clearance:

Looks good!

BTW You might find my Twister (JACE -> ZX81) useful and more details are there: http://www.jupiter-ace.co.uk/hardware_twisterboard.html

McKlaud wrote: ↑Mon Sep 07, 2020 1:55 pm Looks good!

BTW You might find my Twister (JACE -> ZX81) useful and more details are there: http://www.jupiter-ace.co.uk/hardware_twisterboard.html

Thanks, this will and allow a ZX81RAM pack etc. Very useful

I am wondering what ribbon cable length will be tolerated, I guess I can just try and see

The adaptor kit ribbon cable sold for the ZX80 to connect to the ZXpand is approx 4 inches and this works very well.

anightin wrote: ↑Mon Sep 07, 2020 3:31 pm I am wondering what ribbon cable length will be tolerated, I guess I can just try and see

There are a few variables affecting the length tolerance of course and you may well have to suck it and see. However, as an example of length , here is an ACE backplane/expansion-extender designed and built by a relative as a one-off (or rather one for him, and a gift for me). It might give you an idea for the board you intend building though.
The (unattached) cable at the top is ~22cm. One end has an ACE edge connector (well, two in fact which are wired a bit differently) and the other an IDC connector to plug into the main board which, as you see, provides 3 card connectors and a screw terminal block. It's a little hard to see the dark brown board to which the connectors are bolted against the wood surface it's lying on. However, the length of the main board is ~28cm. It's been perfectly stable (and useful) whenever I use a default ACE clone (however, as mentioned elsewhere, I mainly use my own design of ACE clone which has a different expansion bus). The screw block can be a boon for prototyping.

Alan

Thanks both, looking hopeful then.

I've made up a 30cm cable for a first pass. Just waiting for my boards to arrive now

Just keep in mind that you are sending the Z80 address, control and data bus signals down lots of parallel conductors. As the cable length increases, there will be increased crosstalk, and increased stray capacitance. Both will degrade the logic signals.

So keep the cable length as short as practical.

Mark