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Tandy 1000 Programmer's Reference Guide

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Chapter
1
I
System Calls
SetBlock
Modify
Allocated
Memory Blocks
Function Call
4AH
Attempts to “grow”
or
“shrink” an allocated block
of
memory.
En try Conditions:
AH
=
4AH
ES
=
segment address of memory area
BX
=
requested memory area size,
in
paragraphs
Exit Conditions:
Carry set:
BX
=
maximum size possible, in paragraphs (if
the
requested
size
was
not
available
on
a grow
request)
Carry not set:
No error.
Error Returns:
AX
=
9
Invalid block. The block specified in
ES
is not one
allocated via this call.
Arena trashed. The internal consistency
of
the
memory arena has been destroyed. This is due
to
a
user program changing memory that does not
belong to it.
Not enough memory. There was not enough free
memory after the specified block to satisfy the
grow request.
AX
=
7
AX
=
8
Example:
SetBlock
eq”
40H
mov
e5,
block
mov
bx,
newsize
mow
ah,
SetBlock
int
21
H
125

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Tandy 1000 Specifications

General IconGeneral
ProcessorIntel 8088
Processor Speed4.77 MHz
RAM128 KB (expandable to 640 KB)
Operating SystemMS-DOS 2.11
ManufacturerTandy Corporation
Release Year1984
StorageSingle or double 5.25" floppy disk drive (360 KB), optional hard drive
SoundTandy 3-voice sound
PortsParallel, Serial
GraphicsCGA (Color Graphics Adapter)
Graphics Modes320x200, 640x200

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