GE DATANET-30 Programming Reference Manual page 134

DEF 1
DEF 2-10
NES 1
SCN
LDT
Reset flag and read next character. The reader starts paper moving through the
reader or allows the movement of paper to continue.
No effect.
Read flag set (a new character is ready).
Do not use.
No effect.
Register Transfer _ _ _..., T - No effect.
The following example is a few lines of coding which show one way in which paper tape might
be read. In this example, paper tape is punched in 6-level code and 3 characters are ass.embled
into one word. Channels 7 and 8 are not punched.. In this example, the 7 and 8 channels are
transferred but are not used.
Location Instruction Symbol OPR
Operand
x
Remarks
13560 ORG 6000 ORIGIN LOCATION
13560 011000 PIC 0 PUT PAPER TAPE READER ADDRESS IN C
13561 022001 READ NES 1 CHARACTER PRESENT?
13562
121561 BZE
;'(-1
_NO, GO BACK
13563 044044 SL6 R,B YES, SHIFT TO B-REGISTER
13564 022001 NES 1 CHARACTER PRESENT?
13565
121564 BZE
,·~-1
NO, GO BACK
13566 044444 SL6 BR,B YES, SHIFT TO B-REGISTER
13567 022001 NES 1 CHARACTER PRESENT?
13570
121567 BZE
*-1
NO, GO BACK
13571
060444
TRA
BR,B YES, TRANSFER TO B
13572 705576 STB WKSTOR
x
STORE IN MEMORY INPUT AREA
13573 341576
ADO WKSTOR ADD 1 TO INDIRECT MEMORY ADDRESS
13574 771577 XBZ STOP
IS THIS A STOP WORD?
13575
131561 BNZ READ
NO, GO READ NEW WORD
13576
0017 5 0 WKSTOR IND 1000
INDIRECT ADDRESS
13577
777777 STOP OCT 777777
STOP CONSTANT
Initially buffer selector address 0 is put into the C-register. The NESl command tests the
buffer for a character, and status line 1 will remain a 0 until a character is pres.ent. When
the flag sets, the program falls through the BZ E test and shifts the character into the B-register.
When three characters have been assembled in the B-register, they are stored away in memory
and a test is made to see if the last word was a stop signal.
If
the word was not a stop signal,
control is transferred back to the symbol READ and the reading process continues.
NOTE: When tape is loaded in the reader, the tape will stop with a sprocket hole over the read
station. A sprocket hole by itself will set the flag and represents a "blank" character.
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