27 Mar
2002
27 Mar
'02
4:56 a.m.
Hi,
classiccmp(a)classiccmp.org said:
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!
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?
--
Cheers,
Stan Barr stanb(a)dial.pipex.com
The future was never like this!
From: Tony
Duell <ard(a)p850ug1.demon.co.uk>
I wrote:
> After checking the schematic I find that
there is a link. "Use L1 for
1K
> RAM, use L2 for 2K RAM." This tells me
that when a 4118 or two 2114s
are
> used (or a 6116???) there is no need to
change the jumper -- it's only
> required when using a 2KB 2016 or equivalent.
Tony replied:
What is this link connected to? What does it
reconnect?
Ok -- I have yet another version of the schematic here, and it agrees with
the first -- L1 for 1K and L2 for 2K but does NOT specify what this means
in terms of the actual number of RAM ICs onboard.
From looking at the schematic from the ZX-TEAM web
site, I can't see how
either jumper would affect a two-chip configuration. L1
ties the single
RAM chip's A10 to +5V, while L2 ties the single chip's A10 to the A10 line
on the system bus.
Can you make any sense out of this, or is it necessary to be Clive Sinclair
in order to understand it?
As mentioned in a previous post, the 2-RAM-chip ZX81 PCBs I have at hand
have NEITHER L1 or L2 installed.