New ZX80 boards

[zx81jens]

Hi Users!

I found this while surfing the Web:

http://microwave.gr/giannopk/zxcomputer/PCB_Foils.pdf

Maybe this will help a bit

Greetings
Jens

[KnightFire]

Yeah, Grant Searle made that PDF of the issue 2 ZX80 motherboard a year, or so, ago.

[Lee Hart]

Hi Users!
I found this while surfing the Web:
http://microwave.gr/giannopk/zxcomputer/PCB_Foils.pdf
Maybe this will help a bit
Jens

Yes, I used this to guess at the board size. Knowing that the IC pins are on 0.1" centers, I scaled the length and width accordingly.

Grant's PCB drawing shows 15.45cm width.
Jens said his foil measures 15.55cm width.
RWAP's foil drawing shows 15.65cm width.
My Legacy ZX80 board is 15.5575cm width (6.125")

This is the sort of thing that gives me fits when trying to lay out a PC board. I don't know which is correct!

[Paul]

Hi Users!
I found this while surfing the Web:
http://microwave.gr/giannopk/zxcomputer/PCB_Foils.pdf
Maybe this will help a bit
Jens

Yes, I used this to guess at the board size. Knowing that the IC pins are on 0.1" centers, I scaled the length and width accordingly.

Grant's PCB drawing shows 15.45cm width.
Jens said his foil measures 15.55cm width.
RWAP's foil drawing shows 15.65cm width.
My Legacy ZX80 board is 15.5575cm width (6.125")

This is the sort of thing that gives me fits when trying to lay out a PC board. I don't know which is correct!

Just in case you are (still) interested, Lee. I have a ZX80 keyboard membrane from Rich at home and would sponsor it to you.
Just send a PM or an Email to me with your adress if you want me to send it to you.
As these are the only mebranes available at this time it would be our only chance.
CU
Paul

[Lee Hart]

Just in case you are (still) interested, Lee. I have a ZX80 keyboard membrane from Rich at home and would sponsor it to you.
Just send a PM or an Email to me with your adress if you want me to send it to you.
As these are the only membranes available at this time it would be our only chance.
CU
Paul

Hi Paul (and all),
I've been working on the Legacy ZX80 layout. So far, I have moved 30 of the 40 keyboard switches to the locations that I *think* are correct for Rich's membrane. It's pretty tight, and requires that some of the pads overlap. But so far, none of the holes need to overlap, so the board should be possible to fabricate.

Basically, there is one keyboard layout on top for the membrane, and a second keyboard layout on the bottom for the discrete switches. The mounting holes for the discrete switches have to work as feedthru holes, yet miss the membrane pattern.

I think it will work. But it would be great if I could borrow your membrane to be sure! I will send you my address in a personal message.

[Lee Hart]

The ZX80 keyboard membrane arrived from Paul. Thank you for sending it! I matched it up to my revised ZX80 layout, and it fits. The only thing I'll need to change are the outer edges. (assuming that there are supposed to line up with the PCB edges).

BTW, it really does look great, RWAP! Thank you so much for making these. The only suggestion so far is that the shiny surface isn't ideal for a keyboard that will be getting lots of finger prints. If you do another run, a matte finish might be better.

[sirmorris]

It may not be ideal but at least it's authentic..!

Lee - did you make any progress with the shift key problem?

C

[RWAP]

We did consider whether a matt finish would be better on the membranes, but it was considered that for authenticity, they should remain a glossy finish - it is a shame, as matt is much easier to use in artificial light!

[zx80nut]

Hi.

Regarding the board sizing:

My "version 1.3" of the Issue 2 PCB foils has been updated to increase the size slightly to match the (corrected) actual size of 155.5mm x 204mm.

This version will be released on my website shortly...
http://home.micros.users.btopenworld.com/zx80/zx80.html

The keyboard overlay on my ZX80 is actually 157.5mm by 68.5mm, so there is a slight overhang on either side and also on the front of the PCB.

Please refer to the URL shown above to obtain the latest version of the PDF with the PCB layouts.
The latest version is maintained on this page, and other copies may become out of date.

Regards.


Grant

[Lee Hart]

Good timing on this, zx80nut! I have fixed all 40 of the key locations on my ZX80 clone board to match the original. The layout is tricky, but it will work with either the overlay (identical to the stock ZX80), or 40 individual keyboard switches (more reliable and easier to use).

I was still not certain of where the array of 40 keys should be positioned relative to the edges of the PCB. I assumed the overlay's edges were even with the edges of the board. But from your post, it sounds like this isn't a critical dimension -- the overlay may hang over the edges of the board.

This lets me finalize the layout, so I can order new boards!