F L A I l I/o OPERATrONS overlap other
operations in the 70/25.
All r/o instructions are two address (6
On the 70/25 one to eight r/o channels
If an r/o device is busy when an r/o
instruction using that device is at-
tempted, a hold off will occur and the
instruction will be restaticized until the
device becomes available.
After an r/o instruction is performed,
a Condition Code setting of 3 indicates
The direction of operation for all r/o
instructions is from left to right.
The instruction that tests for an error
condition after an r/o instruction is the
POST STATUS instruction.
Unless inhibited an interrupt takes
place after each r/o command.
The purpose of r/o termination inter-
rupt is to transfer the Standard Device
Byte into HSM.
A Post Status Command will terminate,
and control will be passed to the next
instruction if the channel addressed is
If a device is inoperable, and a read
orwrite is directed to it, the Secondary
Indicator of the Standard Device Byte
is set and int-errupt takes place.
What are some ofthe uses of the WRITE
What are the formats of the 70/25 I/O
What does the Sl field contain in an
Write a Read Forward and a Read Re-
verse instruction which will read data
from trunk #2, unit #2, into the area
Write the necessary instructions to:
Read a Card
Punch a Card
Write a message to the console
Read a message from magnetic
Include the sensing, the condition code,
POST STATUS, I/O SENSE, for each