Mode Considerations For Deleted Records; Record I Nsert Feature - IBM 3741 Data Station Reference Manual

Notes:
1. In the Index mode, a record is rewritten even if no
change is keyed to the record. That is, the record has
a D in the first position but the record is not a deleted
record.
2. When the 3747, 3540, or any other system reads a
record, it examines both the data address mark and the
first position in the data record for a D. If the data
address mark identifies a deleted record, but the first
position in the data record is not a D, a halt will occur
with an error condition. Therefore, if the diskettes are
to be processed by other than a 3741 Model 1 or 2, or
a 3742, or if a data set is used as input from a directly
attached 3741, the procedure for deleting records and
preserving the first data character should not be used.
If the diskettes are processed by a 3741 Model 3 or 4,
see IBM 3741 Models 3 and 4 Programmable Work
Station Programming Reference Manual, GA21-9194,
for information on deleted records requirements. Also,
for more information, see Control Records in The IBM
Diskette General Information Manual, GA21-9182.
Mode Considerations for Deleted Records
Enter Mode: Using DELETE REC during enter mode blanks
the current record buffer and positions the cursor at the
first manual position. The previous record buffer is
unchanged.
Update Mode: If, during update mode selection, a deleted
record is read into the current record buffer, the previous
record buffer will contain the same deleted record. If a
deleted record is in the current record buffer when a
record advance occurs during update mode the record is not
transferred to the previous record buffer. If a deleted
record is encountered during record backspacing, the
previous record buffer is not changed.
When deleting a record, the first character is changed to a
D in the current record buffer, "and the remainder of the
content in the current record buffer remains unchanged.
Verify Mode: When selecting verify mode from the index
track, the first nondeleted record in the data set is read
into the current record buffer.
If verify mode is selected from update or verify mode and
the currently displayed record is a deleted one, the next
non-deleted record is read into the current record buffer.
I n either case, the previous record buffer is blanked.
20
When a record advance occurs and a deleted record is in the
hold buffer (next sequential record is deleted), the next
non-deleted record is read into the current record buffer by-
passing all deleted records encountered. If a deleted record
is encountered during record backspacing, the deleted
record is read into the current record buffer with the pre-
vious record buffer unchanged.
When deleting a record, the contents of the previous
record buffer remains unchanged and a record advance
function is performed.
Search Mode: Using DELETE REC during search mode
blanks the current record buffer and positions the cursor
at the first manual position. The previous record buffer
and the record at the current disk address are unchanged.
If the search operation terminates on a deleted record,
both the current and previous record buffers contain the
deleted record.
RECORD INSERT FEATURE
With this feature, you can insert records within a data set
as shown below.
BOE
01001
Current
Record
Address
01005
01006
EOD
10026
EOE
15026
I
Records to be inserted
1
2
3
To insert records into a data set, the record insert function
performs an operation which creates space in the data set
for the number of records to be inserted. The 3741 puts
deleted records in the space created. The deleted records
have a D in position 001 and a \ (inverse slash) in position
002. The remainder of the record is blank.
a
A A
01005
1