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CHAPTER 25
25.
INPUT/OUTPUT FUNCTIONS FOR SUPPORTED DEVICES
In
the
following
description of the 1/0 functions for
~upported
devices these symbols will be used:
Symbol
Meaning
A
A
accumulator
B
B accumulator
X
Index register
cc
Condition
code
z
Zero flag of condition code register (bit
2)
c
Carry
flag
of
condition
code register
(bit 0)
CR
Carriage return
It is assumed that
the
reader
is
familiar
~ith
what
system
function~
are,
how they are invoked; what precautions
. must be taken when testing programs using
system
functions,
and
hoUl
errors are hand.led by system functions (see section
24.8),
25. 1
Supported Devices
MDOS provides input and output functions to
access
the
following supported devices:
MDOS Name
eN
CP
CR
OK
LP
Physical Device
Console keyboard and/or display
Console punch
Console reader
Diskette drive
Line printer
The following sections describe the system functions that are
available for accessing these devices.
25.2 Device Dependent
1/0
Functions
MOOS provides system functions
for
directly'
acc~s$ing
the
console
keyboard,
display;
line printer, and diskette
drives.
All
o~
the functions are accessed
by
executing
an
SWI
instruction
followed
by a function byte.
The value of
Page
25-01
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