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Select search on sequential content from the read index,
enter or update mode. To select this search:
1.
2.
3.
Press FUNCT SEL lower and SEARCH SEQ CON-
TENT. The record currently in the hold buffer is
transferred into the current record buffer and dis-
played.
Press FUNCT SEL lower and DELETE REC to blank
the screen.
Key the search mask into the current record buffer.
4.
Press R EC ADV to start the search.
When the record is found, it is displayed.
Read Index Mode (X)
The read index mode displays records on the index track
representing the volume label, the data set labels, and other
system data. A special procedure is required to write or
delete records in this mode. For data flow, see Figure 13.
The 3741 or 3742 checks to see if the following conditions
have been met in the data set label:
1.
The beginning-of-extent address is less than track 01,
sector 01.
2.
The end-of-extent address is greater than track 74,
sector 26.
3.
The end-of-extent address is less than the beginning-
of-extent address.
4.
The end-of-data address is greater than the end-of-
extent address plus 1.
5.
The end-of-data address is greater than track 75, sec-
tor 01.
6.
The sector is 00 or greater than 26.
7.
The record length is equal to 0 or greater than 128
for the 3741 or the 3742 with the 128 feature or is
not equal to 80 for the 3742.
8.
The third character of the record address of beginning
of extent, end of extent or end of data is other than
O.
9.
The last record read and currently displayed is from
track 00, sectors 1 through .7.
10.
The fourth position of the header 1 field is a number
other than 1.
11.
The record has been deleted.
When a header 1 record in sectors 08 through 26 is read,
the 3741 or 3742 checks the first eight conditions in the
previous I ist. I f any of these conditions exist, a B error is
displayed.
When update, verify, enter, or search mode is attempted
from the index track, all 11 conditions are checked. If any
one of the 11 conditions is present, a B error is displayed.
Modify Mode (M)
Use the modify mode to write data or to delete records on
the index track. Key the record to be written, then select
modify by pressing FUNCT SEL lower and M. The modify
mode can be selected from the read index mode only; if it
is selected from another mode, an M error occurs. No other
mode can be selected from the modify mode. DELETE
REC, RESET, and REC ADV are the only valid keys in the
modify mode. All others give an F error. The mode reverts
to read index after the first keystroke following the selection
of modify mode.
I ndex record is read
from disk into the
.......... - - - - - -
current record buffer
and displayed.
Record advance
transfers the record
to previous record
buffer.
Figure 13. Data Flow for Read Index Mode
Field Totals Mode (F)
•
o
Disk
Select field totals mode to perform offline field totals from
Page 16
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