ZX80 - was: SN76477N

[Tony Duell]

> 
> On 11/11/05 01:14, "Tony Duell" <ard at p850ug1.demon.co.uk> wrote:
> 
> > system unit (with no cover -- the cover was the monitor base), a laptop
> > which was wider than a PDP11 (seriously, it's got a full-size 102 key
> > keyboard. and other similarly 'interesting' products.
> 
> You mean the PPC512 and PPC640? Quite interesting design really - a PC1512
> or 1640 motherboard stuck in a clamshell case with a 7 inch LCD screen and

Not quite. The chips, including the Amstrad gate arrays are pretty much 
the same, but the mechanical layout is different. The PPC has 2 boards 
stacked one on top of the other, with a strange DIN41612-like connector 
(but longer, I think 40 pins in a row) between them.

> full size keyboard. The 640 had twin floppies too. Also ran on batteries

AFAIK both models could take 2 drives and the internal modem option card. 
I have a PPC640, 2 drives, modem, etc, And the service manual + 
programming reference.

> though I can't remember how long they lasted.

IIRC it's 10 C cells, and they don't last that long. I normally run mine 
off a 12V bench supply.

>  
> > Still, for some reason I acturally prefer them to Sinclair's offerings.
> > It may well be because my first computer as a Sinclair (MK14), and I had
> > so many problems with it (both from the manual and the ridiculous design)
> > that I never want to suffer one of his products again.
> 
> >From what I've been told you can blame NatSemi for the design of the MK14,
> not Science of Cambridge - it was a rehash of the SC/MP reference design
> board.....can anyone verify that?

Well, it's probably related to the NatSemi design in that it's a simple 
SC/MP system. But I can't beleive NatSemi used '157s as latches (surely 
that should have been '175), for example.

The rumour I heard was that it was based on a final year undergraduate 
project at Cambridge University (which in turn was probably influenced by 
the NatSemi reference design).. MK14 would have been the correct format 
for a userid at Cambridge at that time I think.

-tony