[BBC-Micro] MOS ROM Structure

[Jonathan Graham Harston]

>Message-ID: <070103005505 at arcade.demon.co.uk>
 
A bit of clarification: not all the ROMs can just be replaced as
the MOS spreads out into some of the sideways ROMs.
 
The MOS code is in "ROM 8" (ie, the bit in memory at &C000),
effectively all of ROM 15 and ROM 14 from &BA00-&BFFF.
 
In the 128K ROM that means:
 
 00000-03FFF MOS, appears at &C000-&FFFF
 04000-07FFF Freely replacable as ROM 9
 08000-0BFFF Freely replacable as ROM 10
 0C000-0FFFF Freely replacable as ROM 11
 10000-13FFF Freely replacable as ROM 12
 14000-17FFF Freely replacable as ROM 13
 18000-1B9FF Freely replacable as a short ROM 14
 1BA00-1BFFF VDU drivers, appears at the end of ROM 14
 1C000-1FFFF Terminal/MOS Utils, appears as ROM 15
 
-- 
J.G.Harston - jgh at arcade.demon.co.uk - mdfs.net/User/JGH
There are three food groups: brown, green and ice cream.