Page of GA22-7000-4 Revised September 1, 1975
By TNL: GN22-0498
2. When service-out or command·· out is raised in response to
status-in during an initial selec-·
tion sequence with the status on
bus-in including attention, con·· trol unit end, unit check, unit ex­
ception, busy, status modifier
(without channel end and device
end), or device end (without
channel end).
3. When a short, control-unit-busy
sequence is signaled.
4. When command retry is signaled.
5. When the channel issues a test I/O command rather than the
command in the current CCW"
1 0 1 The command has been accepted, but
data transfer is unpredictable. This eo de applies from the time a device
comes on the interface until the time it
242 System/370 Principles of Operation is determined that a new sequence
code applies. It may thus be used
when a channel goes into the polling
or idle state and it is impossible to de­
termine that code 2 or 3 applies. It
may also be used at other times when
a channel cannot distinguish between
code 2 or 3. 110 Reserved.
111 Reserved. I/O Address (Locations 185-187): A three-byte
field is provided for storing the I/O address on
each I/O interruption in EC mode. Zeros are stor-
ed at location 185, and the channel and device address­
es are stored at locations 186 and 187, respectively.
Locations 160-167, 180-184, and 188-191 are
reserved for future I/O use.

Operator Section Address-Compare Controls. Check-Stop Indicator .
Configuration Controls.
Display-and-Enter Controls.
Emergency-Pull Switch. Enable-System-Clear Key I MPL Controls Interrupt Key
Load Indicator Load Key.
Load-Unit-Address Controls Manual Indicator Power-Off Key
Power-On Key
Rate Control. Restart Key Start Key. Stop Key. Store-Status Key System Indicator System-Reset Key
Test Indicator Contents
Thermal/CB Power-Check Indicator TOO Clock Key .
Wait Indicator Remote Operator-Control Panel
Customer-Engineer Section The system console provides the functions necessary
to operate and control the system. It consists of the
system control panel and, in most cases, an associat­
ed console device, which may be used either as an I/O device or as a manual display-and-enter device.
The system console may be implemented in various
technologies and configurations; however, certain
functions are basic to all models.
The system-control-panel part of the system con­
sole contains an operator section and a customer­
engineer section.
The operator section provides a means for the
control and indication of power, the indication of
system status, operator-to-system communication,
the control of time-of-day clock security, initial pro­
gram loading, resets, and other controls required by
the operator for intervening in normal programmed
operation. It may include controls used for loading
microprograms into reloadable control storage and
for loading resident diagnostic programs.
The customer-engineer section includes controls
intended only for customer-engineer use. Additional
customer-engineer controls may be available on the
main-storage and channel frames.
System Console
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The console device, when used as an I/O device,
provides a means of communicating control informa­
tion and of entering and displaying text. Implemen­
tation of this device is model-dependent; the device typically may be a keyboard and an associated print­
er or cathode-ray tube (CRT).
The specific console device provided on a paiticu­
lar model of System/370 is described in the Systems
Reference Library (SRL) and System Library (SL)
publications for that model.
Operator Section
The operator section contains the basic controls
required by the operator and the controls required
by the operator for intervening in normal programmed
operation. These controls may be interspersed
with customer-engineer controls and may, depending
on the model, contain switch positions and nomen­
clature additional to those described here.
Machine errors detected during manual opera­
tions do not cause an immediate interruption or log­
out but may, in some cases, create a pending
machine-check-interruption condition. This interrup­
tion request, unless it is removed by the use of a
System Console 243