IBM System/360 System Programmer's Guide

Flags 2 (1 byte)
is used only by the system.
First Two Sense Bytes (2 bytes)
are placed into the input/output block by the system when a unit
check occurs.
ECB Code (1 byte)
indicates the first byte of the conpletion code for the channel
program. The system places this code in the high order byte of the
event control block when the channel program is posted complete.
The completion codes and their meanings are listed under "Event
Control Block Fields."
ECB Address (3 bytes)
specifies the address of the 4-byte event control block that you
have provided.
Flags 3 (1 byte)
is used only by the system.
Channel status Word (7 bytes)
indicates the low order seven bytes of the channel status word,
which are placed into this field each time a channel end occurs.
SIO Code (1 byte)
indicates, in the four low-order bits, the instruction length and
condition code for the SIO instruction that the systerr issues to
start the channel program.
Channel Program Address (3 bytes)
specifies the starting address of the channel program to be
executed.
Reserved (1 byte)
is used only by the system.
DCB ~ddress (3 bytes)
specifies the address of the data control block of the data set to
be read or written by the channel program.
Reposition Modifier (1 byte)
is used by the system for volume repositioning in error recovery
procedures.
Restart Address (3 bytes)
is used by the system to indicate the starting address of a channel
prograro that performs special functions for error recovery
procedures. The system also uses this field in procedures for
making request elements available, as explained under "Error
Recovery Procedures for Related Channel Prcgrams."
Block Count Increment (2 bytes)
specifies, for magnetic tape, the amount by which the block count
(BLKCT) field in the device dependent portion of the data control
block is to be incremented. You may alter these bytes at any time.
For forward operations, these bytes should contain a binary
positive integer (usually + 1); for backward operations, they
should contain a binary negative integer. When these bytes are not
used, all zeros must be specified.
Error Counts (2 bytes)
94
indicates the number of retries attempted during error recovery
procedures.

IBM System/360 Specifications

General

Brand	IBM
Model	System/360
Category	Desktop
Language	English