IBM System/360 20 User Manual

On a Model 20 Submodel 5, the micro program
in main storage may be destroyed when any
of the following conditions occurs:
1. Process Check -- the system halts and
the Process indicator on the CPU is
turned on.
2. Machine Check on the 2520 or 2560 --
the system halts and the Machine Check
indicator on the affected unit is
turned on.
3. Unrecoverable I/O error -- the system
halts and a programmed-halt code is
displayed ~n the E-S-T-R fields of the
CPU console. All programmed-halt codes
are listed in the section
~~oqrammgQ=li~ll~i§£1ays.
If a halt caused by any of these three
conditions occur on a Model 20 Submodel 5
and operation cannot be resumed, the micro
program must be reloaded. This is done by
performing the following steps:
APPENDIX B. MICRO PROGRAM LOAD PROCEDURES
1. Press the I/O Check-Reset key on the
CPU and reset all check lights on the
attached I/O devices.
2. Set the Register tata/Address switches
on the CPU console.
3. Set the Mode switch on the CPU to CPL.
4. Place the micro-program card deck
(supplied by the IEM customer engineer)
in the hopper of the loading unit of
the 2501 or 2520 or in the primary feed
of the 2560.
5. Press the Load key on the CPU console.
If the micro program has been
successfully loaded, the U-L and E-S-T-R
fields on the CPU console will contain all
zeros. If an error occurred during the
loading process, a code will be displayed
in the 0-1 fields on the CPU console. The
code displays that can be handled without
the aid of an IEM customer engineer are
listed below •
.-- ---r --,
I Code Displayed I I
I U L Cause I Restart I
, -r- ~
I 0 0 I Successful load. I Set Mode switch on CPU to PROCESS I
t-----------t I ~
I 0 1 I Read error and/or I Restart the micro program load procedure. I
I I feed check. I I
t------'--------t__ I <-I
I 0 2 I Card missing or out I Check the card sequence in columns 73-80. I
I I
of sequence. I (If the sequence error was caused by a break I
t -+--------------------1 in the numeric sequence, a card is out of I
I 0 3 I Section out of I sequence; if it was caused by a break in the I
I I
sequence. I alphabetic sequence, a section is out of I
I I I sequence) Correct the sequence error and I
I I I restart the load procedure. I
I I I If a card is missing, call the IEM customer I
I I I
engineer. I
L ______________ i- ~ J
Appendix B. Micro Program Load Procedures 167

IBM System/360 20 Specifications

General

Brand	IBM
Model	System/360 20
Category	Storage
Language	English