Date   : Mon, 29 Aug 1994 15:23:00 BST
From   : APM1001@...
Subject: Re: BBC Default boot mode

Hi,

On power on, the BBC reads the state of the dip switches by scanning
the keyboard matrix, the dips are just like keys themselves (either
up or down). I believe that 3 of these combine to make the mode that
the machine boots up in. Also, one bit is used for the Boot type
eg. Shift-Boot, or normal boot. I'll check which ones, It reads it
by poking SHEILA at &FE30??? (i think) to see what state they are at.

Hope this helps

Cheers
-Nigel
(apm1001@...)