Multipunch Operations; Hexadecimal Display; Deleted Records - IBM 3741 Data Station Reference Manual

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MUltipunch Operations
HEX can be used to perform the equivalent of mUltipunch
on card keypunch machines. See Appendix B for card
punch to hexadeci mal conversions.
The important multipunch operations are overpunching
with 11,12, and 0 punch. The following procedures are
valid for overpunching numerics 0 through 9.
11 Punch: For the 11 punch, first press H EX, then press
the
0
key or the dash (-) key, and then the numeric key
(0 through 9). The 11 overpunch in the units position of
a numeric field indicates a negative value.
12 Punch: For the 12 punch, first press HEX, then press
the C key and then press the numeric (0 through 9).
o
Punch: For the 0
punch, first press H EX, then press the
E key and then the numeric key if the numeric is 2 through
9. If the numeric is a 1, the procedure is to press HEX,
then press the 6 key and then the 1 key. I f the numeric is
a 0, do not use HEX, just press the 0 key. (Overscoring a
zero with a zero on a punched card punches the same hole
twice resulting in no change from a single zero punch.
Hexadecimal Display
When hex data is keyed or displayed, not all of the data
represents displayable characters such as an A B C ... or
o
1 2 3 ... When the hex data keyed is not a displayable
character, a hexadecimal display is provided that represents
the eight bit code for the data. The basic display (no bits
on) looks like this:
H
Other lines are added to the display for each bit that is on in
the EBCDIC code.
HEX Value of
Bit Position Bit Position
0- - - - - -8
}
1
-
- - - -
-4
2-
- - - -
-2
3-
- - - -
-1
4 -
- - - -
-8
}
5- - - - - -4
6-
- - - - -2
7 -
- - - -
-1
Add these values together
to get the first hex digit.
Only add those values to-
gether for the I ines display-
ed.
Add these values together
to get the second hex digit.
Only add those values to-
gether for the I ines display-
ed.
Example: Assume the display looks like this:
. . . . . - . . . 8
. . . . . _ . . . 4
The first hex digit is
8
+
4
+
1
=
0
and the second hex digit
is a O. The hexadecimal value is hex DO.
Assume another display looks like this:
. . . . . _ . . . . . 8
. . . . . _ . . . . . 4
. . . . . . _ . . . 8
. . . . . _ . . . . . 4
. . . . . . _ . . . . . . 2
The first hex digit is
8 +
4
+
1
=
0
and the second hex digit
is
8 +
4
+
2
=
E. The hexadecimal value is hex DE.
DELETED RECORDS
A record is identified as either deleted or non-deleted by
the data address mark which precedes the first character
of the record. This address mark (one of two in each
sector of a disk) is not part of the data and is not displayed.
If a record is deleted, the data address mark identifies the
record as deleted. Depending on the procedure used to
delete the record, the first character of the data record
can be preserved or automatically replaced with the
character D. To delete a record and preserve the first
character of the data record, press FUNCT SE L lower
and then press NUM SHIFT with DELETE REC. To
delete a record and automatically replace the first char-
acter of the data record with a 0, see IBM 3741 Data
Station Operator's Guide, GA21-9131.
When the 3741 reads a record, it examines the data address
mark to see if the record is a deleted record. If the data
address mark indicates the record is deleted, a 6 error is
displayed in the status line. Since the 3741 does not check
for a
0
in the first position of the data record, the operator
must use the 6 error to identify deleted records.
To change a deleted record to a non-deleted record, the
record must be rewritten. To do this, key a change to the
record and press REC ADV. To rewrite a record in the
Index mode, press FUNCT SEL lower, press M, and then
press REC ADV.
Operation Modes and Considerations 19