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1. General Description

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 cha ining and assumes that the card

reader is in the "ready automati c

state when the

510

instruction is executed.

Label

Command

Argument

Comments

RDC,\RD

LI,O

DA(IOCD}

Load general register 0 with the doubleword address of the

I/o

con-

trol doubleword for the read card operation.

STARTIO

SIO,10

This instruction starts the card reader (device 3 on lOP O).

TESlIO

TlO,10

This instruction obtains the

I/o

system and card reader status response.

CW,ll

BZTEST

This instruction compares the status response in register 11 with a

"busy" test constant.

BCS,4

TESTIO

This instruction causes a branch back to the TlO instruction if the

card reader is still "busy".

CW,11

ERRCHK

This instruction compares the status response in register 11 against an

error check constant.

BCS,4

ERROR

This instruction causes a branch to a routine that determines the cause

of the error(s}.

BCR,O

DONE

This instruction causes an unconditional branch to another part of the

program, where the card images are processed.

BZTEST

DATA

X'40000000 ' •

This assembl er directive defines the "busy" test constant.

ERRCHK

DATA

X '28FEOOOO '

This assembler directive defines the error check constant.

BOUND

This assembler directive establishes a doubleword boundary for data

to follow.

IOCD -

GEN 8,24

X10E', BA(EBCDIC}

These two assembler directives define the first

I/o

command double-

GEN 8,24

X'241,80

word for the card reader operati on. 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.

GEN 8,24

X'OA', BA(BINARY}

These two assembler directives define the second

I/o

command double-

GEN 8,24

X'04', 120

word for the card read operation. The command doubl eword speci fi es

bi nary read, normal stacker, stack on error in al ternate stacker 2,

store card image in area BINARY, halt on transmission error, and a

byte count of 120.

EBCDIC

RES

This assembler directive reserves 20 word locations (80 bytes) for the

EBCDIC card image.

BINARY

RES

This assembler directive reserves 30 words (120 bytes) for the binary

card image.

Append i x B