Radio Shack TRS-80 Model III - ROM Subroutines

TRS-80
MODEL
III
ROM
Subroutines
The
Model III
BASIC
ROM contains many subroutines that can be cal led by a
zxo
program; many of these can be
called
by a BASIC program
via
the USR function
.
Each
subroutine
will
be described in the format
given below.
Important
Note
Some
of these
ROM addresses
or calling
procedures may
change in
later releases
of the Model III ROM.
We
suggest you design
your
programs
to minimize the
difficulty
of adjusting to these
possible
changes.
{Use EQUates for
all
ROM
calls; modularize
all
uses of
ROM routines; etcetera.)
1.
$NAME
—
Entry
address
2.
Function
Summary
3.
Description
of
function
4. Entry
Conditions
5. Exit
Conditions
6.
Sample
Program
Notes:
1.
The
subroutine
name is
only
for convenient
reference.
It is not
recognized
by the
Computer.
The
$-
prefix
reminds
you that it is
a convenience
name
only.
The
entry
address is
given
in
decimal/hexadecimal
form. (The
hexadecimal
address
will
be given
in this
form:
X'0000'
.
)
This is the
address
you use in
a Z-80
CALL.
BASIC
programmers
store
this
address in the
USR definition
address
(16526-16527).
4,5.
Entry
and exit
conditions
are given for Z-80
programs
. If a Z-80
register is not
mentioned here,
then
you can
assume it is unchanged
by the
subroutine.
6.
Sample
Program
fragments
are given in
Z-80 Assembly
Language
and, where
appropriate, in
BASIC.
Here
are the
subroutines,
arranged
according
to
function.
In the
following
pages,
they
are
arranged
alphabetically.
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