Tandy TRS-80 Owner Manual & Programming Manual page 91

^APPENDIX
E
MEMORYMAP
DECIMAL
0-255
256-1023
1024-1535
1536-2440
2441-top
ofRAM
top
of
RAM
is
16383
for
16K
systems;
32767
for
32K
systems
HEX
0000-00FF
0100-03FF
0400-05FF
0600-0988
0989-top of
RAM
top
of
RAM
is
3FFF
for
16K
systems;
7FFF
for
32K
systems
32768-40959
40960-49151
49152-57343
57344-65279
"
8000-9FFF
A000-BFFF
C000-DFFF
65280-65535
E000-FEFF
FF00-FFFF
CONTENTS
System
Direct
Page
RAM
Extended Page
RAM
Video
Text
Memory
Additional
System
RAM
DESCRIPTION
See
Section
IV
of Getting Started with
COLOR
BASIC
for detailed information.
This
is
used
exclusively
by
DISK
BASIC.
These Random
Access
Memory
locations are allocated
dynamically and
contain the
following:
1.
Random
File Buffer
Area
2.
File Control Blocks
(FCBs)
3.
Graphics Video
Memory
Total buffer
space
for
random
access
files,
256
bytes are reserved
for this
on
start-up. This value
can be
reset
by
the
FILES
statement.
Control data on each
user
buffer.
843
bytes are
reserved
for this
on
start-up.
This value can be
reset
by
the
FILES
statement:
(number
of buffers
set
by FILES +
1)
x 281
bytes.
4.
BASIC
Program
Storage
5.
BASIC
Variable
Storage
6.
Stack
7.
String Space
8.
User
Memory
Extended
COLOR
BASIC
ROM
COLOR
BASIC
ROM
COLOR
DISK BASIC
ROM
Unused
Space reserved
for
graphics video pages.
6144
bytes or 4 pages
are reserved
for this
on
start-up.
This value can be
reset
by
the
PCLEAR
statement:
number
of
pages reserved by
PCLEAR
X
1,536 bytes per
page. (Note: All pages must
start at a 256-byte page boundary
—
i.e.,
a
memory
location divisible
by
256.)
Space
reserved
for
BASIC
Programs and
Variables.
6455*
bytes (16K
systems)
or
22,839*
bytes
(32K
systems) are reserved
for this
on
start-
up.
This value can be
reset
by
different settings of
Random
File Buffers,
FCBs,
Graphics Video
Memory,
String Space
or
User Memory.
Total space
for string data.
On
start-up, 200
bytes
are reserved, but
this
can
be reset
by
the
CLEAR
statement.
Total space
for user
machine-language
routines.
No
space
is
reserved
for this
on
start-up, but
this
can be
reset by the
CLEAR
statement.
Read Only
Memory
Read Only Memory
Read Only
Memory
Inp ut/Output
*Ifyou execute a
PRINT
MEM
command,
on
start-up,
you
will,
get
a
number
a
little
lower than
this
because of
the
overhead necessary
to execute
this
command.
81