Date   : Tue, 08 Feb 2005 09:09:38 +1300 (NZDT)
From   : Michael Foot <mjfoot@...>
Subject: Re: BBC SWRAM module

Quoting Jonathan Graham Harston <jgh@...>:

> > Message-ID:
> <Pine.LNX.4.44.0502071052330.28045-100000@...>
> Chris Johns <chris.johns@...> wrote:
> > On Mon, 7 Feb 2005, Michael Foot wrote:
> > > I agree that it's a homemade job and that whoever did it knew what
> they
> were
> > > doing. I've not seen a schemetic for this type before but it looks
> overly
> > > complex to me. The green wire going to S37 is interesting.
> > > Unfortunately because it is an Econet only machine, I've not go
> around to
> > > testing it out yet.
> > 
> > I notice the lack of (D)NFS chip in that machine - did it come like
> that
> > or did you take it out?
>  
> It looks like the IC between the MOS and BASIC is the DNFS.

That IC is View 2.1. I don't know the origins of the machine and it is exactly 
as I received it. You are right, it does not appear to have (D)NFS installed.

I *should* plug it in and see what *HELP says.

> > I can't quite make out what's under the homemade thinggy, it looks
> like it
> > could be 2 chips "stuck together" - maybe one of those is DNFS and
> the
> > other is the RAM - so the extra logic is to use both in the same
> socket?

Yes, there are 2 chips "stuck together", but I don't know what they are. They 
could be 6264s or larger.

[snip]

> Is there any possibility of you telling us what the small ICs are
> and sketching the wiring arrangement, or uploading a very detailed
> picture of just the ROM area, detailed enough to read the IC
> legends? All I can make out is 74LS02 at the bottom and
> 74LS-something at the top.

Yes, I can do this.

Thanks,

Mike.

--
Michael Foot <mjfoot(at)paradise(dot)net(dot)nz> *
http://homepages.paradise.net.nz/mjfoot/
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