IBM System/360 Operating Guide

address loaded indicate the system state at the
starting point of your program segment.
2. After each run of your program segment you can
then press the System-Reset key once. Then
press the Start key twice. This procedure allows
you to start, using the PSW in location O.
MANUAL INTERVENTION
Various conditions may arise that require some
type of manual operation to be performed. For
example, the hopper on a card reader may empty
(it must be reloaded by the operator). Lights on
the various I/O units indicate the condition of the
I/O units (refer to the specific I/O device publication
for information). The 2030 console, however, does
not explicitly indicate I/O device conditions. In a
basic card system (for example: a CPU, a printer,
a 1052 Printer Keyboard, and a card read-punch),
indicators on the I/O units can be inspected with
little difficulty. As the number of I/O units increases,
however, it becomes increasingly difficult for the
operator to see the indicators on all the I/o units.
How does the operator know when an I/O unit
requires manual attention? A variety'of methods
can be used. Each depends upon the operating
procedures at the installation. Procedures that
can be used are:
• Messages in Main Storage. Messages to the
operator can be placed in storage locations (such
as 0, 1, 2, and 3) and the system programmed to
enter the wait state. When wait state is entered,
the operator can examine the message and per-
form any necessary action. The programmer
should supply information (to the operator) that
describes what the messages Signify.
Note: The system should be programmed to
enter wait state if it cannot proceed because data
is unavailable from an I/O unit (card reader out
of cards).
• If an IBl\l 1052 Printer-Keyboard is used, the
program can be written to type out messages to
the operator when I/O units require attention.
• The program can be written to sound the alarm
(special feature) whenever an I/O unit requires
attention. One of the preceding procedures can
then be used to provide more specifiC information.
MICROPROGRAM TEST ROUTINES
Several test microprograms, normally used by the
IBM Customer Engineer, that are stored in ROS can
be useful to the programmer and operator. Be sure
that all console switches are reset before normal
programming operations are resumed.
Note: These tests disregard storage-protection
requests. Care must be exercised 6.0 as not to
unintentionally alter useful data.
BASIC TEST
This test exercises basic components of the system
and is used to detect malfunctions caused by CPU
circuitry. Functions that control read/write storage
and the I/O channels are not tested by this HOS
routine.
The basic test is initiated when the system is
restarted after a System Reset or when an IPL pro-
cedure is performed, unless the Check Control
switch is set to Disable. The test loops 128 times:
it is normal for all machine-check lights to flash
on and off.
DISPLAY READ/WRITE STORAGE
This test can be used to display successive main-
storage locations as follows:
1. Set the Check Control switch to Stop.
2. Press the System Reset key.
3. Enter the address of the first location to be
dis played, us ing switches F, G, H, and J and
then press the Set IC key.
"1. Enter ROS 2.dclress OBF7, using switches, F,
G, II, and J, and the ROAR Reset key.
5. Press the Start key to display succeeding
locations in the main-storage data register.
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IBM System/360 Specifications

General

Brand	IBM
Model	System/360
Category	Desktop
Language	English