Control Data 3234 Series Hardware Reference Manual page 39

CHECKWORD VERIFY (0044)
The checkword verify code is the only operating mode that does not require a buffer.
On receipt of this function code by the controller, the data within the current cylinder
(or strip in the strip file) is read and checked for an illegal checkword. Operation
commences at the present address position of the read/write heads and continues to the
end of that cylinder (or strip in the strip file).
NOTE
When operating in EOR mode, only one record
is verified; if no record mark is present, the
rest of the file/ cell is verified.
READ CHECKWORD (0045)
The read checkword operation, in conjunction with an input operation, causes the con-
troller to initiate a read operation from the selected storage unit at the address speci-
fied by the contents of the controller address register. This operation is identical to
the 0040 read function except that all checkword(s) read are returned to the data channel
along with the data.
There is one checkword per data block in the disk file and disk drive units. There are
six checkwords per data block in the strip file (refer to Checkword Location).
The operation continues until halted by one of the conditions listed under Select Interrupt
o~ End of Operation.
The following codes select and specify the conditions under which the 0042 and 0043
search compare functions operate, and determine and identify the conditions under which
an end of operation occurs.
MAGNITUDE SEARCH (RECORD
<
BUFFER) (0050)
The magnitude search code modifies the search compare operation so the comparison is
satisfied if the data read (searched) is equal to or less than the output data.
The search is unsuccessful (no compare status bit sets) when the first (high order) un-
masked output data bit is a 0 and the record bit is a 1.
2-16
60333300
B