Topic       : TOS - The Operating System
Author      : 
Version     : tos.hyp (December 19, 2008)
Subject     : Programmieren/Atari
Nodes       : 3010
Index Size  : 93790
HCP-Version : 5
Compiled on : Atari
@charset    : atarist
@lang       : 
@default    : Title
@help       : 
@options    : +g -i -s +x +zz -t4
@width      : 70
View Ref-File12.1.11.2  mmc_flg1_bit4                                           TOS

The lower I/O area ($00FF8000-$00FFFFFF) is not present as such, i.e. 
quite normal RAM may reside there, just as in any other place. In that 
case no distinction will be made between ST-RAM and TT-RAM - the whole 
of the RAM used by MagiC Mac, even that above 16 MB, will be made 
available as ST-RAM.

This means, of course, that in this case programs can make no I/O 
accesses to this area! If this bit is cleared (not set), a program can 
make accesses there nevertheless and count on a bus error if no 
Atari-compatible hardware (such as McSTout, say) is installed there.