Subject: Re: Missing Columns episode 12768 - possible solution ?
To: John Shardlow <>
From: David Jones <>
List: amiga-dev
Date: 08/08/1994 15:09:53
[ Re: missing columns ]

> I find it very interesting that the same problem exists on both 
> NetBSD and Linux yet I experience no problems with the display
> when using AmigaOS.
> One of these days I'll get to the bottom of this.......
> John

Has anyone done the obvious here?

Can a debug msg be put into the kernel giving the physical address of the start
of the frame buffer?  (More precisely: start of each plane, plus interleave
modulo)  Then, using some kind of utility (I can provide
you a very primitive one), read the relevant portion of /dev/mem.
(Clear the screen, put some text in the upper left corner, then use the rest
of the display to dump the first 256 bytes or so of memory.)

The question: do the bit patterns in chip RAM correspond to what is displayed,
or not?  If not, is there any pattern to the mis-correspondance?

I take it this is a stock 3000?

David Jones, M.A.Sc student, Electronics Group (VLSI), University of Toronto
           email:, finger for PGP public key
        finger for latest Toronto Free-Net information
          Click me!