060

From: Doug Little <doug_at_innerworkings.co.uk>
Date: Thu, 4 Mar 1999 10:21:19 -0000

>Steve also said there is an illegal instruction for the
>040/060 around the sixth or seventh instruction at startup
>that the AB must be taking care of somehow.


That's true. There are illegal 040+ opcodes kicking around in the ROM, most of them pretty early in the boot sequence. I think the AB manages to mask these out somehow, perhaps using address masks via the logic chips. From what I remember, they are almost all 68030 PMMU instructions and are therefore easy to spot.

The simplest solution is to edit these opcodes out of the rom image and burn the image onto another chip. I can't think of any other practical way to get around it.



Doug Little - Software Engineer / 3D Graphics Research

Inner Workings PLC

 "doug_at_innerworkings.co.uk"
 "doug_at_lookinglass.freeserve.co.uk"
Received on to. mars 04 1999 - 17:31:54 CET