Xerox 7120 - Page 14

Table 5. Card Reader I/O Instruction Execution Response
Status Bitst
Instruction
CCI or 0
CC2 or C Significance
SIO
a
a
I/O address recognized and SIO accepted.
a
I I/O address recognized, but SIO not accepted.
1
a
Selector lOP is "busy" (appl icable only to Si gma 5/6/7).
1
1
I/O address not recogn i zed.
HIO a
a
I/O address recognized and card reader "not busy" when
halt occurred.
a
1 I/O address recognized and card reader "busy" when halt
occurred.
1
a
Invalid code.
I 1 I/O address not recogn ized.
no 0
a I/O address recognized and SIO can currently be accepted.
a 1
I/O address recognized, but SIO cannot currently be accepted.
I a
-
Selector lOP is "busy" (appl icable only to Sigma 5/6/7).
1
1
I/O address not recognized.
TDV
a
a
I/O address recognized.
a
1
Invalid code.
1
a
Sel ector lOP is "busy" (appl i cab I e onl y to Si gma 5/6/7).
1
1
I/O address not recognized.
AIO
a
0
Normal interrupt condition present (no "unusual end").
a
1
Unusual interrupt ("unusual end") condition present.
1
a
Inval id code.
1
1
No interrupt condition present.
t
In Xerox 530 and Sigma 2/3 computers, "0" represents the Overflow bit and "C" represents the Carry bit; in other
Xerox
computers,I"CCl" and "CC2" refer to condition code bits.
8 Card Reader
Status Response
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