Topic       : Pure Assembler Documentation
Author      : John Kormylo
Version     : PASM.HYP 1.0
Subject     : Documentation/Pure Assembler
Nodes       : 740
Index Size  : 20262
HCP-Version : 3
Compiled on : Atari
@charset    : atarist
@lang       : en
@default    : 
@help       : Help
@options    : +g -i -s +x +z -t4
@width      : 75
View Ref-File[ TT RAM ]

... starts at $1000000, beyond the address space available to the
68000 CPU.  This memory is directly accessed by the CPU, not through
the MMU chip.  Consequently it is faster to access than ST RAM.

Since the video chips cannot access TT RAM at all, programs which
handle video images in their BSS segment must be loaded into ST RAM.
Programs which handle video images in heap memory must Malloc() from
ST RAM.

Since the DMA chip used for floppy and ACSI port I/O uses 24 bit
addresses, it also cannot access TT RAM.  TOS I/O functions use a
buffer in ST RAM and copy to/from TT RAM.

The header of an executable program file contains flags on whether
to load a program or satisfy calls to Malloc() using TT RAM (see
Linker Options).

In addition, the TT supports a new function, Mxalloc(), which allows
one to specify whether to use ST RAM or TT RAM.

See also Atari Memory Map.