New ZX80 boards

[KnightFire]

I can't justify the cost of an "authentic" membrane; especially without an "authentic" case to go with it.
I'm interested in Lee's Legacy ZX80 board, as is. However if things are changing, I would love to see composite video out, and an easy way to remove the keyboard section. Or perhaps a more "functional" Legacy ZX81 board with those features.

[Paul]

I would love to see composite video out, and an easy way to remove the keyboard section

Well you are lucky.
Composite video out is already implemented in the prototypes, the modulator is left out. And If you have a saw (which I have), and dare to use it (which I don't) on this beautiful PCB, then the Keyboard is easily to be taken off as the cut line is already painted on the PCB and the wholes for the connectors are there.

[KnightFire]

Apologies Paul, I was being flippant, I'm very pleased with Lee's board design and hope to be privilaged to get a copy of V2 in my own hands.

[Lee Hart]

Hi Lee - I have the drawings for the membrane with measurements which I can email to you if this is something you would like to investigate.
Rich

A question for Rich (or anyone else who knows the answer):

Rich's keyboard drawing shows it is 156.5mm wide (6.1614"). Is this the actual width of a real ZX80 board? Or is the keyboard overlay wider or narrow than the PC board?

Rich's keyboard drawing shows it is 68.8mm high (2.709"). Does this also match the real board (i.e. is the bottom edge of the keyboard exactly even with the lower edge of the PC board)?

My present Legacy ZX80 layout is slightly different (6.125" wide by 2.75" high for the keyboard). I'm going to try to change it, but need to know *exactly* what size the PC board should be, and where this keyboard overlay fits onto it. Thanks!

[RWAP]

I can't answer this one - I sent a ZX80 motherboard and what was left of an original keyboard to the company who took the measurements from it.

It makes more sense in mm than inches!

[Lee Hart]

I can't answer this one - I sent a ZX80 motherboard and what was left of an original keyboard to the company who took the measurements from it.

It makes more sense in mm than inches!

Thanks Rich. Maybe someone else has a real ZX80 board they can measure.

The mm dimensions are smaller, but that may be because they measured them in mm and only bothered with 3 significant digits.

My board layout software lets me choose dimensions in inches or mm when I start. Since so many of the parts have inch spacings (IC pins on 0.1" centers), that's what I used. It's too late now to switch it to mm.

[zx81jens]

Hi Lee!

I measured it with a good ruler.

The foil from Rich (RWAP) has "exactly" the same extent -it is also that thick (as far as I could see that).

The dimensions:

Width = 155.5 mm (15.55 cm)
Depth = 68.5 mm (6.85 cm)
Height (thickness) = 0.5 mm (0.05 cm)

The two (ZX80-original foil and that from Rich) fit 100%. I think you don´t have to change so much...

Greetings
Jens

[Lee Hart]

Hi Lee!
I measured it with a good ruler.
Width = 155.5 mm (15.55 cm)
Depth = 68.5 mm (6.85 cm)
Height (thickness) = 0.5 mm (0.05 cm)

The two (ZX80-original foil and that from Rich) fit 100%. I think you don´t have to change so much...
Jens

Thank you, Jens. That is *part* of what I need. I need to know exactly where the foil sits on the actual PC board. The holes in the back of the foil for each key need to sit exactly on top of the "comb" fingers on the PC board.

If the foil is exactly the same size as the real ZX80 board (the bottom, left, and right edges are identical), then I can get the dimensions from Rich's drawing.

If the ZX80 board is (for example) wider, so the foil sits ??.? mm away from the board edges, then I need to move the "comb" fingers for each switch to match.

[Paul]

I can't answer this one - I sent a ZX80 motherboard and what was left of an original keyboard to the company who took the measurements from it.

Hi Rich,
if we are having an extra pcb for the membrane, could you think of having the ZX80 membrane produced with the ZX81 writing on it? Maybe not shiny but ZX81 like to fit on this PCB?
It would then of course also fit the original ZX80, just in case anybody would upgrade his ZX80 with the "new" ROM

[RWAP]

I really think that for the costs involved, this would not be a worthwhile project, although I realise it is mainly the design costs which would be different (the same tooling should be able to be used).

I would have thought with the current market in ZX80s being more along the lines of people collecting the originals, they are more likely to want to downgrade back to a ZX80 than upgrade to a ZX81 ROM !