The 3490-C22 is a 36-track, 1 Control Unit, 2-drive, Autoloader, tape subsystem. The Model C22 is a low-cost, rack-mountable member of the IBM 3490 Magnetic Tape Subsystem Enhanced Capability family, providing significant performance and cartridge capacity improvements for midrange systems. The 3490E Model C22 is fully compatible with existing 3490E models, using both the Cartridge System Tape and the longer 3490E Enhanced Capacity Cartridge System Tape, and are read-compatible with earlier cartridge formats for ease of migration. The Enhanced Capability format (36-track bi-directional recording), together with standard Improved Data Recording Capability (IDRC) and the higher capacity tape, dramatically increase overall cartridge capacity. This increased capacity and standard Automatic Cartridge Loader (ACL) on the C22 model combine to address the data capacity requirement for unattended backup on mid-range systems. Utilization of ES Connection (ESCON*) Channels provides new possibilities in performance, connectivity, and remote tape operations. This model is supported on AS/400*, RS/6000*, and ES/9000* systems.

The 3490 Magnetic Tape Subsystem Enhanced Capability Model C22 is a rack-mountable unit designed for mid-range systems providing the following functions:

3490E Model C22 has an Enhanced Capability format (36-track, bi- directional recording) read/write head providing approximately 2X the cartridge capacity of the previous models of the 3480 or 3490 Base models, independent of IDRC. The bi-directional head writes 18 tracks from load point to physical end of tape and then writes the other 18 tracks from physical end of tape to load point. Therefore, fully written tapes are positioned at load point, virtually eliminating the rewind operation. The 2Mb buffer and microcode load provide improved autoblocking increasing cartridge capacity and performance. Autoblocking is always invoked; IDRC invoked is considered normal operations. IDRC may be suppressed, via software only, for special requirements (such as writing tape labels). Half full cartridges (written to physical end of tape) rewind at an average speed of 5 meters per second. The "LOCATE" function has been enhanced to accommodate the bi-directional format. For instance, if the desired record is close to the load point but on the inbound tracks, "LOCATE" reads down the outbound tracks past the desired record, stop, switch to the inbound tracks, and read the desired record, eliminating the time required to search the entire recorded tape.

The 3490E Model C22 writes only the 36-track format introduced with the previous models of the 3490E A10, A20, B20, B40, D41, and D42; however, for migration purposes the model C22 reads previous 3480 and 3490 formats, with or without IDRC.

Control Unit reliability/availability is provided by reducing the number of electronic cards providing room for a maximum of two in any combination of ESCON Adapters, Parallel Adapters, or SCSI-2 Adapters. ESCON provides enhanced connectivity.

Unique microcode and host software is required to support this product. The customer may need JCL changes for 3490 generics or esoterics.

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