Message-ID: <727@vax135.UUCP>
Date: Mon, 9-Jul-84 08:49:55 EDT
Article-I.D.: vax135.727
Posted: Mon Jul  9 08:49:55 1984
Date-Received: Tue, 10-Jul-84 01:28:20 EDT
Organization: AT&T Bell Labs, Holmdel, NJ
Lines: 98


TI-99/4A Memory Map

 > 0000  Console Rom;
	   Interupt vectors, XOP vectors
	   GPL Interpreter, Floating
	   POINT routines, XMLINK veectors,
 > 1FFF	   Low-level cassete DSR etc

 > 2000  Low Memory Expansion Ram;
	   Varies according to the loader
	   used (Assembly). Generally
 > 3FFF	   not used by XBASIC programs.

 > 4000  DSR ROM;
	   Device service routines.
	   Determined by CRU bit setting
 > 5FFF	   Disk Controller, RS232 etc.

 > 6000  Cartridge Port (ROM & MINI MEM)
	   12k of XBASIC ROM. Upper 4k
	   @ >7000 - >7FFF is flipped
	   to page in another 4k for a
 > 7FFF	   total of 12k.

 > 8000  RAM Mem. Mapped Devices - VDP,
       GROM, SOUND, SPEECH.
       >8000 Duplication of scratch pad
       RAM at >8300 - >83FF
       >8100 Dup. as above
       >8200 again
       >8300 Scratch Pad RAM
       >8400 Sound Chip
       >8800 VDP READ DATA
       >8802 VDP STATUS
       >8BFF
       >8C00 VDP WRITE DATA
       >8C02 VDP READ/WRITE ADDRESS
       >8FFF
       >9000 SPEECH READ
       >93FF
       >9400 SPEECH WRITE
       >97FF
       >9800 GRON/GRAM READ DATA
       >9802 GROM/GRAM READ ADDRESS
       >9BFF
       >9C00 GROM/GRAM WRITE DATA
       >9C02 GROM/GRAM WRITE ADDRESS
       >9FFF

 > A000  HIGH MEMORY EXP RAM
	    XBASIC high memory usage,
	    Free space end pointed to
	    by CPU RAM PAD address >8366

	    Numeric Values
	    Line Number Table
	    XBASIC Program Space

 > FFFF  for a total of 24k bytes.


Additional Memory Space not in the CPU
address space;

VDP RAM >0000 - >3FFF     16k bytes.
       This is the console RAM space,
       and is separate from the rest of
       the CPU memory. Without memory
       expansion, XBASIC and BASIC
       programs reside here. (BASIC does
       not use expansion memory.)
       (Assembly language does not use
		 this area.)


This covers the memory map for the 994a
Later I will put up the full map for the
VDP.

Note; BASIC does not use memory expansion
at all. Only XBASIC, Assembly, FORTH etc.
do use it. Chunks of memory are used by
various periphals as buffers, thus the
amount indicated by CALL SIZE is right.
By using CALL FILES(1) followed by NEW,
you can get back some, but disables the
disk system. If you don't have it instal-
led, but have mem exp. you will have more
memory to use automatically. (ever look
at apple ? out of 48k or 64k you end up
with only ~32k or 48k when periphals are
enabled)

	Gene Sampieri
	ATT-BL
	(201)949-4707
	vax135!ees