IBM System/370 145 Manual page 173

1. Generate an OS operating system for the Model 145. and specify
required parameters that describe the 1·400/7010 emulator program
to be used with this operating system. (Generating an operating
system for the Model 145 is discussed in section 60.)
2. Generate the desired 1400/1010 emulator program.
3. Add required OS job control and emulator control statements to
the exis·tiIig 1400/1010 programs that are to be emulated on the
Model 145.. Subject to the cond'itions stated previously in this
section, modification of 1400/1010 programs mayor may not be
required. Optionally. 14001'1010 programs can be placed in a
library (POS) by using the OS IEBUPDTE utility program.
4. Tapes in 1400/1010 mode with blocks shorter than 18 bytes or
longer than 32K must be preprocessed.
5~ Disk files must be transferred to Model 145 direct access devices
by using the steps already outlined.
6. Optionally. routines to support features and I/O devices not
handled by the emulator program can be written and placed in a
library. The generated 1400/7010 emulator program will cause
them to be loaded.
When installation of a 1400/1010 emulator is being planned.
consideration ,should be given to the factors that affect the performance
of emulated 1400/7010 jobs. Throughput of 140:0/701,0 jobs is affected by
the mix of CPU and I/O operations executed by the compatibility feature
and the amount of interference from higher priority partitions or
regions.
A
large fact'or in performance is the way I/O operatioQ,S are
handled. The following steps can be taken to achieve improved emulator
job throughput if enough processor storage is available:
1. Allocate one buffer to each access mechanism simulated instead of
sharing buffers among multiple access mechanisms. (Do not use
the shared buffer option for disk data sets unless processor
storage is limited.)
2. Allocate two buffers to each tape data set instead of one.
3. Convert 1400-format tape files to VS or VBS format for emulator
processing.
4. Using the Tape Preprocessor, reblock tape files containing short
blocks.
5. Do not use the Track Overflow feature for emulated disk data sets
unless direct access space is at: a premium.
os 1410/1010 EMULATOR PROGRAM SUPPORT
The OS 1410/7010 Emulator program can emulate a small 1410 system on
a 160K Model 145 with the 1401/40/60, 1410/7010 Compatibility feature
and enough I/O devices for the operating sys.tem and emulated 1410/7010
devices.
The partition or region size required depends on ~he features, I/O
devices, and buffering used and on the size of the system being
emulated. The emulator program size varies from a minimum of
approximately 23,500 bytes, for a basic system with unit record I/O
device support only, to'a maximum of approximately 43,000 bytes (1410)
or 46,600 (1010) for all special features and unit record, tape, and
disk support.
A
large 1010 syst.em--100K, 14 tape units, each with a 1K
A Guide to the IBM System/370 Model 145 163