- IBM 3310 Direct Access Storage
- Models A1, A2, B1 and B2 announced January 30, 1979
and withdrawn June 16, 1986
The IBM 3310 Direct Access Storage was a compact, economically
priced, high-performance direct access storage device
for use with the IBM
4331 Processor. The 3310 used a fixed media design.
Heads, arms and the media were packaged in a fixed,
sealed disk enclosure providing for increased data density.
The sealed disk enclosure design assured a reduction
in disk surface contamination and resulted in improved
reliability. Operator involvement in auxiliary storage
management was eliminated.
- Stored 64.5 million bytes of data in each of its
drives, Up to four strings of four spindles each could
be attached to a 4331 Processor for a maximum of 1.032
billion bytes of online data.
- Available in four models for configuration flexibility:
- Models Al and A2 consisted of one and two drives
with associated controls which attached to the
4331 via its DASD Adapter.
- Models B1 and B2 were one- and two-drive units
which attached through a Model A2.
- Low-priced single drive increments provided for
granularity of capacity growth.
- Used fixed block architecture. Physically, data
were stored on the disk in 512-byte blocks, providing
logically continuous data. Software support mapped
the data into the format required for user records.
- More data could potentially fit on a track due
to the data structure used in fixed block architecture,
providing increased capacity.
- DASD space was specified as a number of blocks
on the device up to a maximum of 126,016 blocks, making
space definition independent of tracks and cylinders.
- The device independence achieved provided for easy
use and simplified later migration.
- Used a new, lightweight, low-inertia actuator driven
by a voicecoil motor, providing a 27 millisecond average
access time. This simple design required less power
than previous actuators.
- The IBM 3310 contained rotation position sensing
as a standard feature which could enhance subsystem
- The DASD Adapter on the 4331 provided direct, low-cost
attachment for the IBM 3310 without need for a control
unit. Direct processor attachment of up to strings
of eight 3340 actuators also was available as a special
feature of the Adapter. A DASD Adapter with 3340 so
attached operated in count-key-data emulation mode
under DOS/VSE, VS1 or VM/370.
- An optional 2311 and 2314/19 compatibility feature
allowed these devices to be emulated on the IBM 3310.
Use of this feature allowed most DOS or DOS/VS programs
written for the IBM 2311, 2314 or 2319 to be executed
- By installing a special feature, DASD Adapter could
read data from an IBM 3348 Data Module which was recorded
on an IBM System/3 Model 12 or 15, to aid in conversion
from a System/3 to 4331 Processor.
- An optional Block Multiplexer Channel on the 4331
allowed direct attachment of 2311 and 2314/19 DASDs,