Date   : Thu, 02 Jun 2011 11:53:25 +1030
From   : station240@... (paul aslin)
Subject: Model B with video corruption

I've got a Model B here, with all sorts of video corruption. Tried several
replacement vidprocs and removing IC 15 (74LS273), but the fault is still
there. Also swapped IC 14 (74LS245).

One thing I did find was the fault takes a lot longer to appear (after entering 
CLS) with the econet 68B54 removed. Also the machine completely hangs if
NFS is swapped for DNFS, nothing wrong with the later rom as I downloaded
it and used it in an emulator.

This got me thinking, is this a problem with the hardware address decoding ?
Rather than the RAM I mean.

The address decoding does look rather maze like, but at least the chips are
easy enough to find.