IBM System/370 145 Manual page 165

tapes are also supported by data management (the sequential access
methods) and thus they can be processed
by
user-written Assembler
Language programs.
The 3803/3420 Magnetic Tape Subsystem (Version 4 only) '. This tape
subsystem is supported as an I/O device for the same functions as 2400-
series tape units. This includes support of tape switching (two control
units only), Seven Track. andOUal Density features. (Note that 200-BPI
density tapes are not supported because the Seven Track feature includes
only 556- and 800-BPI densities.) The Two-Channel Swi-tch is supported
for alternate path switching betwelen two channels in the same sy~tem.
The data security erase command is supported by the MTC command for
magnetic tapes. When an MTC command with a DSE parameter is issued,
tape is erased up to the location IOf the tape indicate marker. If the
command is issued when the tape is at load point, the entire contents of
the tape, including all labels, ar·e erased up to the end-of-file marker.
Such a tape must be reinitialized or have a tapemark written on it
before i t is used again. Utility
~~upport
is provided only by System
Utility Programs (370N-UT-491).
The 3410/3411 Magnetic Tape Sub:e;ystem (Version 4 on.1y). Support of
this tape subsystem functionally identical to that provided for 2400-
series tape units is provided by d,ata management. The data security
erase command is supported by the l!t1TC command for magnetic tapes, as
described for -the 3803/3420 Magnetic Tape Subsystem.
The 3505 Card Reader (Version 4 only). This reader is supported at
the GET/PUT macro level by the Asslembler Language for basic read
functions, stacker selection, and Icolumn binary mode. The 3505 is also
supported by all DOS high-level languages to the same extent that
support for card readers is providled currently. In addition, the OMR
feature is supported by ANS Full COBOL Version 3 Release 2, ANS Subset
COBOL Release 2, RPG II, and the Assembler Language. Support of the RCE
feature is provided in the Assembl4er Language and RPG II.
The 3505 is also supported as a SYSRDR, SYSIPT, or SYSIN device and
by POWER II for basic read functiollS. If OMR or RCE is to
be
used by an
Assembler Language program, the 3505 cannot also be used as the SYSRDR,
SYSIPT, or SYSIN device.
support of 3505 features by the Assembler Langauge is as follows:
• Stacker selection into stackers 1 and 2 is provided. If a request
for stacker 3 is received, the card is placed in stacker 2 by the
3505. If a request for stackel:' 2 is received and the Selective
Stacker feature is not install.ed, the 3505 places the card in
stacker 1. No indication of either action is given to the user
program.
• Card Image support is provided as follows. Either EBCDIC or column
binary read mode is established at OPEN time, depending on the user
specification, and this mode r4emains in effect until the file is
closed. Thus input decks that contain cards with EBCDIC and column
binary punching in the same card or a mixture of cards punched in
one mode or the other must be handled by the user with the EXCP
macro.
• Either OMR or RCE support can be requested only in the DTFCD macro.
DT'FDI can be used to support the 3505 only for basic read functions.
The OMR or RCE format to be us~~d must be supplied in the first card
of the input deck. Once the file has been opened and the format has
been estab1ished, the format r~~mains in effect until the file is
closed or until unit exception (end of file) on the 3505 is accepted
by the system.
A Guide to the IBM System/310 'ModeJL 145 155