Xerox 7120 - Programming Examples; Sigma 5-9 Programming Example

APPENDIX B. PROGRAMMING EXAMPLES
SIGMA 5-9 PROGRAMMING EXAMPLE
The following partial program is intended to illustrate the use of the I/O instructions and the card reader responses to
these instructions. The program is coded as a nonrecursive routine that reads one EBCDIC-punched card and one
binary-punched card. The program does not use the interrupt system, but does exit to another routine (not shown)
that deals with specific error conditions. Also, the program uses command chaining and assumes that the card
reader is in the "ready automatic" state when the SIO instruction is executed.
Label
RDCARD
STARno
TEsno
BZTEST
ERRCHK
10CD
EBCDIC
BINARY
Command
LI,O
510, 10
no, 10
CW,II
BCS,4
CW,II
BCS,4
BCR,O
DATA
DATA
BOUND
GEN 8,24
GEN 8,24
GEN 8~ 24
GEN 8,24
RES
RES
22 Appendix B
Argument
DA(IOCD)
3
3
BZTEST
TEsno
ERRCHK
ERROR
DONE
X '40000000'
X'28FEOOOO'
8
X'OE', BA(EBCDIC)
X'24',80
X'OA', BA(BINARY)
X'04', 120
20
30
Comments
Load
general register 0 with the doubleword address of the I/o con-
trol doubleword for the read card operation,
This instruction starts the card reader (device 3 on lOP 0).
This instruction obtains the I/o system and card reader status response.
This
instruction compares the status response in register 11 with a
"busy" test constant.
This instruction causes a branch back to the no instruction if the
card reader is still "busy".
This instruction compares the status response in register 11 against an
error check constant.
This instruction causes a branch to a routine that determines the cause
of the error(s).
This
instruction causes an unconditional branch to another part of the
program, where the card images are processed.
This
assembler directive defines the "busy" test constant.
This assembler directive defines the error check constant.
This assembler directive establishes a doubleword boundary for data
to follow.
These two
assembler directives define the first I/o command double-
word for the card reader operation. The command specifies EBCDIC
read,
normal stacker, stack on error in alternate 2, store card image
in
area EBCDIC, command chain, halt on transmission error, and a
byte count of 80.
These two assembler directives define the second I/O command double-
word for the card read operation. The command doubl eword speci fies
binary read, normal stacker, stack on error in alternate stacker 2,
store card image in area BINARY, halt on transmission error, and a
byte count of 120.
This assembler directive reserves 20 word locations (80 bytes) for the
EBCDIC card image.
This
assembler directive reserves 30 words (120 bytes) for the binary
card image.
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