Xerox Sigma 6 Reference Manual page 95

condition code is set, register R + 1 is loaded as shown
above, and register R is loaded as follows:
The current command doubleword address has the same in-
terpretation as for the instruction 510.
Affected: (R), (Ru1), CC1,CC2
Condition code settings:
2 3 4 Result of TIO
o
0
o
o
TDV
I/O address recognized and acceptable
SIO is currently possible.
I/O address recognized but acceptable
SIO is not currentl y possible.
lOP address recognized but device con-
troller either is attached to a "busy"
sel ector lOP that cannot return status at
this time or, for specific device con-
trollers, is currently "busy" with another
device. No status information is returned
to general registers.
I/O address not recognized; no status in-
formation is returned togeneral registers.
TEST DEVICE
(Word index alignment, privileged)
TEST DEVICE is used to provide information about a device
other than that obtainable by means of the TIO instruction.
The operation of the selected lOP, device controller, and
device is not affected, and no operations are initiated or
terminated. The responses to TDV provide the program with
information giving details on the condition of the selected
device, the number of bytes remaining to be transmitted to
or from memory in the current operation, and the present
point at which the lOP is operating in the command list.
If the R field of the TDV instruction is 0, or if CC 1 (as a
result of the execution of this instruction) is a 1, the con-
dition code is set, but no general registers are affected.
If the R field of TDV is an odd value, the condition code
is set and the device status and byte count are loaded into
register R as follows:
Bit
Position Function
0-7
8-15
Unique to the device and device controller.
Same as for bits 8-15 of the status information for
instruction 510.
The count information shows the number of bytes remaining
to be transmitted in the current operation at the time of the
TDV instruction. If the value of the R field of TDV is an
even value and not
0,
the condition code is set, register
R +
1
is loaded as shown above, and register R is loaded as
follows:
The current command doubl eword address has the same in-
terpretation as for the instruction
510.
Affected: (R), (Ru 1), CC 1
Condition code settings:
2 3 4 Result of TDV
a a
o
a
I/O address recognized.
I/O address recognized and device-
dependent condi ti on is present.
lOP address recognized but device con-
troller either is attached to a "busy"
selector lOP that cannot return status at
this time or, for specific device con-
trollers, is currently "busy" with another
device. No status information is returned
to general registers.
1/
0
address not recogn i zed; no status in-
formation is returned to general registers.
AIO
ACKNOWLEDGE INPUT/OUTPUT INTERRUPT
0/Vord index al ignment, privi leged)
AIO is used to acknowledge an input/output interrupt and to
identify what I/O unit is causing the interrupt and why. Bits
21,22, and 23 of the effective virtual address of the AIO in-
struction (the 10 P portion of the I/o sel ection code field)
specify the type of interrupt being acknowl edged. These bits
should be coded
000
to specify the standard I/O system interrupt
acknowl edgement (other codi ngs of these bits are reserved for
use with special I/o systems). The remainder ofthe I/o se-
I
ection code field (bit positions 24-31) has no other use in the
standard I/o interrupt acknowledgement because the identi-
ficationoftheinterruptsourceis one of the responses of the
standard I/o system to the AIO instruction.
Standard I/O system interrupts can be initiated for the fol-
lowing conditions:
Interrupt t
Status
Condition
prerequi si te bit set
Zero byte count
IZC= 1 10
Channel end
ICE = 1
11
t
rzc ,
ICE, IUE, HTE, and SIL refer to flag bits in the lOP
command doublewords (see Chapter 4).
Input/Output Instructions 87