Tandy TRS-80 - 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