GE DATANET-30 Programming Reference Manual page 101

Receive - Hardware Scan
Location Instruction Symbol OPR
Operand Remarks
REM
SAMPLE HARDWARE SCAN RECEIVE
PROGRAM
05670
ORG
3000 ORIGIN 3000
01400 $SCW3 EQU
768
SCAN WORD STARTING ADDRESS
05670 377777
NBIT18 OCT
377777 MASK FOR RECEIVE FLAG
05671
030001
START SCN 1
SCAN BIT BUFFER
05672 603060
LDB $SCW3
LOAD CHARACTER BEING RECEIVED
05673
141671 BPL *-2
CHARACTER NOT IN, GO BACK
05674
401670
LDA NBIT18
CHARACTER IN, GET MASK CONSTANT
05675
533060
NAM
$SCW3
MASK OFF RECEIVE FLAG
Transmit - Hardware Scan
Location Instruction
Symbol OPR
Operand
Remarks
01750 ORG
1000
ORIGIN LOCATION 1000
01000 $SCW1 EQU
513 SCAN WORD ONE
01200 $SCW2 EQU
641 SCAN WORD TWO
01750 030001 SCN
1 SCAN BIT BUFFER
01751 603050
LDB $SCW2
LOAD SCAN WORD TWO
01752 141750 BPL *-2
TRANSMIT FLAG NOT SET, GO BACK
01753 603070 LDB $XWORD
LOAD CHARACTER TO BE TRANSMITTED
01754 703040 STB $SCW1
STORE IN SCAN WORD ONE
01755
601767 LDB BIT18N
LOAD MASK
01756 733050
NBM $SCW2 MASK OFF TRANSMIT FLAG
f
01767 377777
BIT18N OCT 377777
MASK CONSTANT
01600 $XWORD EQU 896
TABLE LOCATION, NEXT CHARACTER TO
XMIT.
Next, is a simplified example of a Program Interrupt Executive Routine containing a Scan instruc-
tion. At Symbol PIEl is found the Store Flip-Flops instruction. This saves all the branch and
control flip-flops from the last instruction executed. Next, all the registers are stored and the
SCN (Scan) instruction is issued. Upon leaving the Scan instruction, the registers and flip-
flops are restored and control is transferred back to the program which was interrupted.
If control of mode conditions within the bit buffers is required, it should be noted that the indi-
vidual channels must be set to their appropriate mode before entering the Scan Operation
(Receive or Transmit Mode).
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