Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!acorn!osmith
From: osmith@acorn.co.uk (Owen Smith)
Newsgroups: comp.sys.acorn
Subject: Re: Upgrading the RAM
Message-ID: <5012@acorn.co.uk>
Date: 6 Feb 91 21:26:33 GMT
References: <1991Feb6.143949.19191@cbnewse.att.com>
Sender: osmith@acorn.co.uk
Distribution: comp
Organization: Acorn Computers Ltd, Cambridge, England
Lines: 36

In article <1991Feb6.143949.19191@cbnewse.att.com> macduff@cbnewse.att.com
(Roger R. Espinosa) writes:

>Anyone have any advice? Instructions (like, "Where *is* the RAM
>located inside the A410?" :-) would be greatly appreciated, too.

The RAM on a 400/1 series machine is right at the front of the main PCB,
hidden underneath the floppy and hard disk drives. On a 410/1 and 420/1,
there are 8 chips soldered into the PCB, and 24 sockets to accept the
remaining 3 MB. On a 420/1, eight sockets already have chips in, these are
the eight that are interleaved with the 8 chips soldered in (makes one
rwo of 16 chips). Since you have 2 MB RAM, this should be the situation in
your machine. The other 16 sockets in a row need chips fitting to go up
to 4MB. So persuading people to do a 2 -> 4 MB upgrade should be simple, as
it is just 16 chips instead of 24.

Note that to get at the RAM chips you will
definitely have to draw the main PCB of the machine out. You can avoid
losing your CMOS RAM settings though - the battery lead is just long enough
to let you pull the board out far enough to get at the RAM chips. You will
need to remove the podule backplane, power connectors, floppy and hard
disk cables, fan leads, and the six way speaker/LEDs connector.

Once you've got the chips in, the RAM size links should be set as follows:

        LK15    LK14
1M       b       b
2M       b       a
4M       a       a

Anything beyond 4MB is an add-on board, although I haven't seen any of them.
I suspect they occupy a podule slot or two.

Owen.

NOTE: This is NOT an official Acorn statement on this subject.