IBM System/370 Manual page 90

The 7080 object programs to be emulated can be placed in the input
stream, on tape, or in a sequential data set on disk (including a
partitioned data set). A DO statement in the input stream describes
their location. The required 7080 emulator control statements can
be provided via the operator console or in a card, tape, or disk
sequential data set identified by a specially named 00 statement
(SYSEMCTL). They can also
be
placed in the input stream or in a
partitioned data set (as members).
The 7080 Emulator program operator commands provided can be entered
via the operator's console or the input stream (located in the emulator
control statement data set). These commands provide simulation of
7080 commands on the Model 165 operator's console. In addition, they
allow the operator to request a listing of an entire emulator program
area or of emulated 7080 main storage within an emulator partition
or region only.
If multiple console support (MCS) is included in the
os
control
program generated, emulator program messages can be routed to a specific
console device so that emulation messages are isolated.
Assuming that the 7080 (or 705 I, II, and III) programs to be
emulated do not use facilities or I/O devices unsupported by the Model
165 7080 Emulator program, the following is required:
• OS job control and any necessary Model 165 1080 emulator control
statements must be supplied for each 7080 object program. Changes
to existing object programs and 7080 control statements are not
required. (This is true for 7080 programs being executed on a
7080 system or emulated on a Model 65.)
• Tape volumes containing files with records longer than 32,755 bytes
must be preprocessed by the tape formatting program,. Tape written
in either seven- or nine-track 1080 mode can be used without
modification. (Consideration should be given to reblocking files
with short blocks in order to improve execution time and reblocking
files with long blocks to reduce processor storage buffer
requirements.)
• Those 7080 programs that use unsupported I/O devices or facilities
can be modified to remove the unsupported item and then emulated,
or these programs can be rewritten to run in System/370 mode.
The internal performance (that is, the speed of performing 7080
CPU instructions weighted by frequency of use) of the 7080 Emulator
program for the Model 165 is approximately 2 times that of a 1080
system. The throughput achieved by the integrated 7080 emulator
operating on the Model 165 versus that obtained using an IBM 7080 is
dependent on the characteristics of the 7080 program being emulated,
the hardware resources available to the 1080 emulator, and the number
of other jobs operating concurrently with the emulated 1080 job(s).
Emulator performance is improved when each 7080 channel is emulated
with a single Model 165 channel (2860, 2880, or 2810 selector
subchannel). Total system throughput should be improved by use of
integrated, rather than stand-alone, emulation.
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