Input/Output Control Blocks
The 10CB (input/output control block)
is
the interface be-
tween
the
APl
or
BASIC
interpreter and
the
I/O supervisor.
When
the
APl
or
BASIC interpreter executes an
APl
or
BASIC statement
that
requires an I/O function,
the
APl
or
~BAS'IC'
interpreter places the appropriate I/O code
in
the
approp.r:ia1;e
10CB and branches
to
the I/O supervisor. The
I/O supervisor executes the I/O function specified by
the
,liOcodeand
places a return code
inthe
IOCB
to
inform
the
APl
or
BASIC interpreter how
the
110
operation
is
,completed. This return code
is
checked by the
APl
or
BASIC interpreter.
The following 10CB formats are the same for both languages
unless specified otherwise:
COMMAND 10CB (BASIC ONLY)
Hex
Displacement
o
Length
Form
Binary
Binary
Description
Defines
the
device assigned
to
the 10CB:
Hex
00
Display screen
Hex
04 Keyboard
Hex
01
ROS
Hex 05 Printer
Hex
OE
- Tape
Hex
08
- Expansion feature
1
Specifies subdevice:
Hex
00
Not used
Hex
80
Built-in tape unit
Hex
40 Auxiliary tape unit
Hex
08
- Serial
110
command device
Hex
04 - Serial
110
output
device
Hex
02 - Serial
110
input device
Hex
20 - Serial
110
BASIC
load
Hex
40 - Serial
110
BASIC save
1 Hardware and communications device address
is
hex
OS.
Serial
1/0
device address
is
hex
OA.
6-16
/
\.
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