Texas Instruments 990 Operation Manual page 99

~-------
~
945255-9701
user flags
buffer addr
buffer length
char count
Bit 0 - reserved.
Bit I - unrecoverable I/O error.
Bit 2 - end of file was encountered.
(The character count indicates
whether any data was transferred.)
Flags indicating additional processing
requirements. Bit 3 is the character
I/O flag. Character I/O applies only
to the logging device (data terminal)
and is ignored in cassette I/O. One
character at a time will be read to
or printed on the logging device. If
the character I/O bit is set, any RUB
OUT or backspace character encountered
in a read from the logging device will
be placed in the uset's buffer.
The absolute memory address of the start
of an I/O buffer.
The maximum number of characters which
may be input.
The number of characters actually
input or output.
An I/O supervisor call may be coded in assembly language as follows:
XOP @IOC, 15
IOC BYTE
0,0
PRB
BYTE 9,7 Read from LUNO 7
DATA
a
System flags/user flags
DATA
BUFADR Buffer address
DATA
80 Buffer length
DATA
a
Character count
'3.5.2.1 Open. The open supervisor call forces a playback/record initialization (to allow a change
of mode if the mode is incorrect) of a tape ca~ette.
Supervisor call code: 0
I/O operation code:
0
Calling parameters:
luno Logical unit number of the drive on which the tape cassette is mounted.
3-61
Digital Systems Division .