IBM System/360 Operating Guide

IBM 2030 SYSTEM CONTROL PANEL
The IBM 2030 Central Processing Unit is provided
with a number of indicators and manual controls
that permit operation of the system in any of several
modes, and observation of the results of any opera-
tion. These indicators and controls are assembled
on a panel (Figure 2) that serves as both an operator's
system control console and an IBM Customer Engi-
neer's panel. The lower right-hand portion of the
console is designated as the Operator's Control
Panel (OC P). This section contains four push but-
tons, three 16-position rotary switches, and six
indicators. Except for the nomenclature printed on
the panel, the OCP is identical on all CPU's (Central
Processing Units) in System/360. The OCP contains
all controls and indicators necessary for normal
problem-program processing.
OPERATOR'S CONTROL PANEL (OCP)
This section of the 2030 console (lower right corner)
has the following controls and indicators:
Power-On Key
The power-on sequence for the CPU and all on-line
I/O units starts when this key is pressed. A system
reset function occurs. All data-flow registers (but
not the general-[Xlrpose or floating-point registers)
are reset. as are any priorities that happen to turn
on. The CPU clock is reset to prevent access to
storage so that information in storage is not dis-
turbed. Hence, system power can be turned off
and restored without destroying information in main
storage.
The I/O units are sequenced ON one by one.
If power cannot be brought up for a unit, further
power-on sequencing is interrupted (console Power
On light remains off) until corrective action is
taken for that unit. All on-line I/O units are also
reset. The po\ver-on sequence bypasses off-line
6
I/O devices. The time required for a power-on
sequence depends on the number of on-line I/O
units.
Note: The follo\\ing procedure must be used when
applying or removing electrical power to input/
output devices:
1. Press the 2030 Stop key and wait for the l\lanual
light to come on.
2. Set the Rate switch to the Single-Cycle position.
3. Press the 2030 Start key.
4. Turn power on or off on the I/o unit.
5. Set the Rate switch to the Process position.
6. Press the console Start key to resume opera-
tion.
This procedure ensures that the system is in a
cycle in which read/write storage is not being
accessed. Thus, any electrical surge on the chan-
nel that might have been caused by applying or
removing power to the unit does not affect the
contents of storage.
If power is removed from the last I/O unit
(because maintenance is required) on a channel.
the line terminators must be relocated in order to
continue CPU operations. The last I/O unit on
any channel must be on as long as the system is
on.
Power-Off Key
This key removes power to the CPU and all on-line
I/O units. The contents of main storage are not
altered during the power-off operation. except that
if a storage-read cycle has been taken (the Allo\\,-
\!.,Trite indicator is on), a manual-\\Tite cycle is
forced to ensure that the contents of the location
just read are not lost.

IBM System/360 Specifications

General

Brand	IBM
Model	System/360
Category	Desktop
Language	English