IBM System/370 145 Manual page 131

20:27 THE 3410/3411 MAGNETIC TAPE SUBSYSTEM
The 3410/3411 Magnetic Tape Subsystem extends the new dimension of
price performance and reliability, availability, and serviceability
provided by the 3803/3420 Magnetic Tape Subsystem to users of half-inch
tape who require data rates of less than 120 KB. The 3410/3411
subsystem offers phase-encoded data. recording and data rates of 20 KB,
40 KB, and 80 KB at 1600-BPI densit.y for Models 1, 2, and 3,
respectively. In addition, the tot.ally new, compact physical design of
this subsystem minimizes floor space requirements while still permitting
some flexibility in the arrangement of the units within the subsystem.
The 3410/3411 subsystem attaches to System/370 Models 135, 145, 155,
and 158 and to System/360 Models 22 through 50. It offers significant
advantages to Model 30 and 40 users with 2415 or 2401 Models 1, 2, and 4
in their tape configuration. The tape commands, status responses., and
basic sense data of this tape subs:Y'stem are compatible with those of
2400-series and. 3420 tape units. Therefore, existing Model 30 and 40
programs for 2400-series tape units will operate without change on the
Model 145 (subject to the restrictions stated in section 10:05) to
handle operations on 3410/3411 subsystems with comparable features.
System/360 users without any tapes installed will find that the'
3410/3411 subsystem offers lower cost entry into tape processing.
The 3410/3411 subsystem consists of Models 1, 2, and 3 of the 3411
Magnetic Tape Unit and Control dnd Models 1., 2, and 3 of the 3410
Magnetic Tape Unit. A 3410 consists of a single tape unit so that a
subsystem can include an odd number of units (a 3410 advantage when
compared to 2415 configurations). One 3411 must be part of every
subsystem since the 3411 contains the tape control functions and power
supply required to operate its own tape unit and the 3410 tape units
that can be attached to it.
Each model of the 3411 can control only one tape speed. Therefore,
different models of a 3410 tape unit cannot be attached to a given 3411
model. A 3410/3411 Modell subsystem can consist of from one to four
tape units--one 3411 Model 1 unit and up to three 3410 Modell units. A
3410/3411 Model 2 or Model 3 subsystem can include from one to six tape
units--one 3411 unit and up to five 3410 units, all of the same model as
the 3411. The Additional Tape Units feature is required for the 3411
when more than three 3410 tape units are attached. A 3410 Modell can
be field-upgrad~d to a Model 2 or 3 while a Model 2 can be field-
upgraded to a Model 3. Field upgrades of 3411 models are possible also.
A significant advantage of the 3410/3411 tape subsystem is the
relatively smaller amount of floor Hpace it requires when compared with
2400-series tape units. This reduction is achieved by the integration
of the control unit with one of the tape units, the compact physical
size of the units themselves, and a new unit design that reduces the
amount of floor space required for service clearance.
The 3410 tape unit is shown in. Figure 20.27.1. The 3411 and 3410
have the same dimensions: 31 inches across the front, 32 inches high in
the front, 39 inches high in back, .and 27 inches deep_ A pair of units
in a 3410/3411 subsystem (including tape control) is approximately the
same width across the front as a pair of 2415 tape units with tape
control (2415 Model 1 or 4) and as ·two 2401 tape units, which require a
stand-alone control unit. The depth of a 3410 is aboQ.t the same as that
of a 2401 and a 2415 but the 3410 iH slightly more than half the height
of 2400-series units.
The 3411 and 3410 units have been designed such that normal servicing
can be accomplished by access to the front of the unit. Thus, less
clearance space is required, and the rear of any unit or of the
A Guide to the IBM system/370 Model 145
121