IBM System/370 145 Manual page 188

• Tota1 system throughput can be increased by operation of the
os
DOS
emulator in a multiprogramming OS environment and by using the
staged I/O option of the OS DOS emulator. The latter permits
emulated DOS programs to use the data transcription facilities of
the OS reader interpreter and output writer to handle their unit
record functions. Use of the staged I/O option of the OS DOS
emulator also eliminates the necessity of dedicating unit record
devices to DOS emulation.
All operating environments, control program facilities, I/O devices,
and telecommunications terminals supported by DOS Versions 3 and 4
(Releases 25, 26, and 27) can be emulated, wit:h the following
exceptions:
• Autotest
• OLTEP (which does not produce meaningful results)
• Model-dependent functions such as CS/30, CS/40, and the DIAGNOSE
instruction (1400 emulation can be handled using the Model 145 OS
1401/1440/1460 Emulator program)
• Emulation of emulators that operate under DOS, for example, Model
145 integrated 1400/7010 emulators that operate under DOS
• QTAM
• 1259, 1412, and 1419 Magnetic Character Readers
• 1287 and 1288 Optical Character Readers in document mode if response
times are required for pocket selection
• 1445 Printer
• 2260 Display station (local)
• 7710/1112 Audio Response Units
• storage protection within the DOS system being emulated (among the
DOS supervisor and partitions)
• DOS (and OS) direct access volumes having nonunique volume serial
numbers online concurrently
In addition, executable DOS programs cannot be handled that:
• Rely on known timing relationships of the DOS system
• Depend on HALT I/O (except for BTAM programs), READ DIRECT, WRITE
DIRECT, or DIAGNOSE instructions for their operation
• Depend on the PCI flag in a CCW (this flag is ignored by the
emulator)
• Modify .or use information in ccw's after the CCW list is initiated
with a START I/O instruction and before the I/O operatian terminates
• Initiate the same CCW list for an I/O operatian on mare than one I/O
device concurrently
• Specify data chaining in a CCW list when the DOS file is read via
the OS input stream .or written via the OS output stream
178
A Guide ta the IBM System/370 Model 145