Date   : Fri, 03 Jun 2011 14:04:30 +0100
From   : jumbos.bazzar@... (Mark Haysman)
Subject: Model B with video corruption

Could be other faults as well, but that screen noise is almost definately a 
bad memory chip, just need to do some pokes and peeks to the CAS1 memory 
range to find what one it is.

Mark.



  ----- Original Message ----- 
  From: paul aslin
  To: bbc-micro@...


  > Is the contents of the screen memory
  > wrong or is it only what is on the screen that is wrong? If the screen 
memory
  > is corrupt, is non-screen memory corrupt too? Is there corruption in all
  > screen modes?

  I don't think its the memory itself, noise is rather odd to say the least.
  http://s1092.photobucket.com/albums/i405/station240/bad%20B%20video/
  View from 1 to 5.jpg and that is the order the noise appears in.
  Of note is this is a 20k screen mode, and the top potion is never 
corrupted. By my calculations this is &3000-&3FFF. Something screwy going on 
with the addressing.