Hi,
ard_at_p850ug1.demon.co.uk (Tony Duell) said:
> > > As mentioned in a previous post, the 2-RAM-chip ZX81 PCBs I have at hand
> > > have NEITHER L1 or L2 installed.
> >
> > Just to confuse things further the schematic I have shows L1 pulling pin
> > 19 of the 4118 up to 5V when that's installed, and no L2 at all!
>
> What else (other than L1) is pin 19 of the 4118 (the 24 pin chip
> location) connected to? Anything?
>
Nothing.
> > The text refers to 2x2114 or a 4118 installed in the UK version and a
> > 2K option for export - possibly there are 2 versions of the board?
>
> OK, I've pulled my ZX81 apart. The PCB claims to be 'Issue 1'.
>
> There are 3 solder pads to the right of the 24 pin chip location :
>
> o
> L1
> o
> L2
> o
>
> (where 'o' is a solder point on the PCB). You link the top and middle
> pads fro L1, and the middle and bottom pads for L2.
>
> The top pad is connected to +5V. The middle pad to pin 19 of the 24 pin
> chip. The bottom pad to A10 on the Z80 (at least).
That agrees with my actual board - also an "Issue One".
Mine's working quite nicely now, all I need to do is find the Forth
manual to find out how to use some of the features. There must be
some cassettes and program listings somewhere as well.
--
Cheers,
Stan Barr stanb_at_dial.pipex.com
The future was never like this!
Received on Fri Mar 29 2002 - 03:11:03 GMT