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0(0)<br />
DATA EVENT CONTROL BLOCK -- BSAM<br />
DECSDECB<br />
Event <strong>Control</strong> Block<br />
4 (4) 6 (6)<br />
DECTYPE, DECBPTR DECLNGTH<br />
Type of I/O Request or Address of next DECB Length of Key and Data<br />
8 (8)<br />
12 (C)<br />
16 (10)<br />
20 (14)<br />
DECDCBAD<br />
Address of DCB<br />
DECAREA<br />
Address of Key Data or of user specified channel program<br />
DECIOBPT<br />
Address of lOB<br />
DEC NEXT<br />
Address of the Next Address Feedback Field<br />
Figure 13A. Data Event <strong>Control</strong> Block -- BSAM<br />
Offset<br />
o (0) 4<br />
4 (4) 4<br />
4 (4) 2<br />
4 (4)<br />
5 (5)<br />
Bytes and<br />
Alignment<br />
6 (6) •• 2<br />
8 (8) 4<br />
Name<br />
Field<br />
DECSDECB<br />
DECBPTR<br />
DECTYFE<br />
Byte l<br />
1 •••<br />
.xxx xxxx<br />
Byte 2<br />
1 •••<br />
.1 ••<br />
•• 1.<br />
.•. 1<br />
x.x<br />
.1 ••<br />
•• 1. ••• 1<br />
DECLNGTH<br />
DECDCBAD<br />
DATA EVENT CONTROL BLOCK -- BSAM<br />
Field Description, Contents, Meaning<br />
Event control block.<br />
23 (17)<br />
For IBM 1419 Magnetic Character Reader and IBM 1215<br />
Optical Reader Sorter:<br />
A pointer to the next DECB to be tested for<br />
completion by the CHECK macro instruction. (DECB<br />
chaining applies to the use of more than one device.)<br />
This field in the last DECB must be zero.<br />
For other than IBM 1419 Magnetic Character Reader and<br />
IBM 1275 Optical Reader sorter:<br />
Type of I/O request.<br />
Type of length operand:<br />
S coded for length.<br />
(Reserved bits)<br />
Type of operation:<br />
READ SF<br />
READ SB<br />
WRITE SF<br />
WRITE SO<br />
(Reserved bits)<br />
WRITE SZ<br />
WRITE SFR<br />
140 OS <strong>System</strong> <strong>Control</strong> <strong>Blocks</strong> (Release 21.7)<br />
Length of key and data.<br />
Address of the DCB to which this I/O request is<br />
related.
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