Appendix Ji Basic Memory Map - Radio Shack TRS-80 Model 4 Owner's Manual

Appendix JI BASIC Memory Map
0000H to 25FFH Operating System Reserved for TRSDOS
operations.
2600H to 2FFFH Overlay Area Used alternately by TRSDOS
and BASIC. Whenever you use
a TRSDOS library command,
TRSDOS uses this area to
store the program that will
perform the command. BASIC
reloads this area with its data
when you return from
TRSDOS.
3000H to 85FFH BASIC
Reserved for BASIC.
8600H to User's BASIC Reserved for your
Bottom of Stack
Program programs, variables, strings,
and arrays.
Bottom of BASIC stack and Contains the stack used by
Stack to HIGH$ File Control BASIC and the File Control
or User-Defined Block(s) Block(s) (FCBs). Each FCB
top of memory requires 564 bytes of
(M) storage. The number of FCBs
that your system has is
~-
selected with the command:
BASIC (F
=
n), where 'n'
specifies the number of files
that can be open at anyone
time. (One additional 564-byte
block is always allocated and is
reserved for use by BASIC.)
User-Defined Assembly This area exists only if you
top of memory
language routines create it with the command,
(M) or HIGH$
callable from BASIC (M
=
address) where
to HIGH$ BASIC. 'address' specifies the last
address that BASIC will use.
The area between "M" and
HIGH$ is used to store
assembly language routines
that are called by BASIC
programs.
A-101