Inaccuracies in my advert?

[RWAP]

I have been contacted by someone on eBay who says that they used to work for Sinclair in 1979 and claims that the details on my advert for the ZX80 keyboard overlay contains various inaccuracies showing that I know very little about the ZX80.

I have asked him for more information, and suggested he join the forums and provide us with some reminiscences about his time at Sinclair (or rather Science of Cambridge) - however, does anyone know what he might be on about?

[sirmorris]

I think anyone that pretends that they can remember anything from 1979 is a big fat liar. Just my opinion

[RWAP]

I remember all the strikes and power cuts from 1979 even though I was only 11....

[Andy Rea]

Hmm i'd say it's a fair ebay advert...

But if i had to be ultra picky, i'd try rewording it to omit the word switches..

sits on top of the switches built into the ZX80s motherboard.

reword to

" sits on top of the contact patches built into the ZX80s motherboard. '

maybe

regards Andy

[Moggy]

I think anyone that pretends that they can remember anything from 1979 is a big fat liar. Just my opinion

!959 now that was a good year Me and Janet M in an old Anderson shelter at the back of Her old mans, club!!

1979 the only thing I remember, Charlie, is that it was very dull in comparison.

(Nurse pills please)

Regards Moggy

Ps Rich the strikes were early to mid 70's Miners in 72 and a 3 day working week in 74.
Knocked hell out of My pay packet; work 3 days sign on for the other 2. Happy times?
No!

[Fruitcake]

I would guess the person that made contact was referring to this paragraph:

The other main reason for replacing the keyboard has to be where you acquire a ZX80 computer which has been 'upgraded' to a Sinclair ZX81 (reducing its value substantially). This upgrade consisted of a replacement ROM chip and a new keyboard overlay which reflected the extra commands and facilities on the Sinclair ZX81 home computer. Now you can revert the keyboard to a ZX80, all you then need to do is to find what happened to the original ROM chip.

The keyboard overlay for the ZX80 did not replace the existing ZX80 membrane but was a thin sheet that sat on top of it. It was not glued down but held in place with the same plastic clips used to hold the keyboard section of the ZX80 PCB to the bottom casing.

This photo shows the holes in the corner of the upgrade membrane and the black plastic clips that held it in place:
http://www.flickr.com/photos/9574086@N02/1222148262/

Restoring the ZX80 keyboard is therefore simply a matter of removing the overlay to reveal the original membrane underneath. It is then only necessary to locate and refit the original ROM as you have stated. If the original ROM is not available then it is possible to directly drop in a 2532 EPROM. The only difficulty is locating such an EPROM (I believe they are no longer manufacured) and the fact that it requires a 25V programming voltage which many modern programmers do not support.

[sirmorris]

I can burn 2532s if anyone needs one.

C

[Moggy]

I can burn 2532s if anyone needs one.

C

How about 2764 eproms Charlie? If I sent You one could You Burn the h4th rom onto it?
Happily pay costs for time etc.

Regards Moggy

[sirmorris]

Sure, no problem. Do you actually mean 2764?

C

[Moggy]

Sure, no problem. Do you actually mean 2764?

C

As far as I can recall Charlie Its the same eprom David Husband used to supply when bought new, it came with a small adapter board. I have a standard 81 rom on a 2764 with all the fiddily bits of cross connected wire etc which works but is not very tolerent of my battery backup boards (timing issues??).
Barring this is it possible to use said h4th on Your super zeddy expander thingy?
In which case deep joy.

Let Me know either way; Many thanks Charlie.

Moggy