ZX-81 Re: Sinclair ZX-80 - test-drb@ccmp.vtda.org

27 Mar 1998

To implement the "slow" mode, the ZX81 has the NMI line connected to
something or other. I have one Timex 1000 and a ZX81, the difference
being 1k (1k in the ZX81, 2k in the Timex) but of course, everyone "has"
to have one of the wobbly 16k packs! 

For those interested, you can roll your own ZX80, thanks to the lack of
custom chips! (That's right - Z80, RAM, ROM, and a handfull of TTL
chips...) Schematics and ROM images (also for ZX81) are at
http://www.babytalk.demon.co.uk/zx80/zx80.html
--------------------------------------------
Joachim Thiemann
DSP Coder, Castleton Network Systems
I doubt therefore I might be.

...
  -----Original Message-----
 From:	John Ruschmeyer [SMTP:jruschme@exit109.com]
 Sent:	March 26, 1998 22:52 PM
 To:	Discussion re-collecting of classic computers
 Subject:	Re: ZX-81  Re: Sinclair ZX-80

  Hi Lynn,

   Timex 1000s are EASY to find!  I've passed up dozens of them at  yard
  sales.  I have four that I ended up with for one
reason or another.  BTW
  I found a ZX-81 the other day. Is anyone familar
with it?  What's  the
  difference between it and a ZX-80?  
 The ZX-81 is basically a ZX-80 with an enhanced ROM and some extra
 circuitry
 which let it display while computing (SLOW mode).

 The TS-1000 is a ZX-81 with 2K of RAM instead of 1K.

 <<<John>>> 