Texas Instruments 990 Operation Manual page 98

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The individual supervisor calls and their operation codes are listed in table 3-2.
Table 3-2. List of Supervisor Calls
Supervisor Call
I/O - Open
I/O - Read ASCII
I/O - Write ASCII
I/O - Write End of File
End of Program
Binary to Decimal ASCII
Decimal ASCII to Binary
Binary to Hexadecimal ASCII
Hexadecimal ASCII to Binary
Supervisor Call
Code (Hexadecimal)
0
0
0
0
4,
A
B
C
D
I/O Physical Record
Block Operation Code
(Hexadecimal)
o
9
B
D
3.5.2 I/O SUPERVISOR CALLS. The data block for an I/O supervisor
call
consists of the
following two blocks (contiguous on a full-word boundary):
• A two-byte block that specifies a zero for an I/O call in the first byte and has the
second byte set to O.
• A seven-word control block, called a Physical Record Block (PRB). This control block
specifies the type of I/O operation to be performed and the input and output
parameters.
The format of the physical record block is as follows:
o
The parameters are:
i/o op
luno
sys flags
1ST BYTE
7 8 2ND BYTE
<i/o op> <luno>
<sys flags> <user flags>
<buffer addr>
.<buffe r length>
<char count>
The I/O operation requested
The logical unit to which I/O is to be
performed.
15 '
Flags indicating the status of a completed
I/O operation:
3-60
Digital Systems Division
"' .