IBM System/370 Guide

access devices cannot be executed on a system without such
channels and devices.
2. The same control program, MFT or MVT, must be used for both
systems.
3. Consideration should be given to the processor storage sizes
of the two models when determining such factors as size of the
scheduler, language translators, and linkage editor(s) included
in the generated system.
4. Processing programs that are to run on both models must use
instructions and features common to both systems. An Assembler
Language program that uses the new general purpose instructions
for the Model 165 or byte orientation can be executed on a Model
155 but not on Models 50 or 65.
In order to generate an operating system that is portable between
the Model 165 and the Model 155, 50, or 65, the following steps are
required:
1. A complete system generation must be performed to generate an
operating system for the Model 165. The IPL-time system/operator
communication option must be requested so that options specified
can be altered during IPL,.
2. A nucleus generation should then be done for the alternate
system. The model number specified (in the SUPRVSOR, SECMODS,
CENPROCS macros" etc.) will be that of the alternate system,
not the Model 165.
3. Additional link-edits must be performed to add model-dependent
routines to the generated multiple nucleus operating system.
Specifically, MCH or SER and EREP model-dependent routines for
the secondary system must be included, as appropriate.
4. If extended precision floating-point divide is used in processing
programs, the following steps should be taken. SYS1.LINKLIB
contains two divide simulation routines. One uses extended
precision hardware, the other does not. When a full generation
is performed for the Model 165, a calling mechanism is set to
request the divide routine that uses extended preCision
instructions at execution time, since the Model 165 contains
these instructions.
Therefore, the divide simulation routine that does not use
extended precision should be transferred from SYS1.LINKLIB to
another library and given the same member name as the divide
routine with extended precision instructions. When the operating
system is executed on a Model 165, SYS1.LINKLIB should be used
by extended precision programs. When the operating system is
executed on a Model 50 or 65, the alternate library should be·
used.
Whenever a new program that is to be used on both systems is added
to a library or if ~he Model 165 hardware configuration changes, the
user must consider whether or not portability is affected.
60:20 USE OF OTHER PROGRAMMING SYSTEMS
Subject to the restrictions stated in Section 10:05, users of OS PCP,
DOS, TOS, BOS, and OS MFT and MVT control programs not generated for
a Model 165 or non-IBM-supplied control programs can execute their
existing control and processing programs on a Model 165 with a hardware
94

IBM System/370 Specifications

General

Brand	IBM
Model	System/370
Category	Server
Language	English