Motors & Drives Information

A Reliable, Autoloading, Streaming Half-Inch Tape Drive

HP's NEWEST HALF-INCH TAPE DRIVE, the HP 7980A (Fig. 1), is an autoloading, reel-to-reel, horizaontally mounted, streaming drive that reads and writes in two standard nin-track formats: 6250 GCR and 1600 PE. This maintains compatibility with previous drives and tapes, and important feature because half-inch tape is still a significant standard in the computer industry for backing up, archiving, and interchanging computer data.

The HP 7980A provides computer system users with a reliable, low-cost, backup device for large amounts of online disc memory. It does this with higher performance and reliability and lower cost than its predecessor, the HP 7978B, which it replaces. IT reads and writes at 125 inches per second, roughly 60 percent faster than the HP 7978B. The HP 7980A can rewind a 2400-foot tape in less than 90 seconds, reducing overall data transfer times significantly. The HP 7980A is 40 percent more reliable, a result of the increased use of VLSI components to reduce parts counts even further than was achieved on the HP 7978B. The monthly maintenance cost of the HP 7980A is half that of the HP 7978B. Horizontally mounted in a standard-width rack cabinit, the HP 7980A is 8.75 inches high, a third the size of the HP 7978B. This saves valuable floor space and allows better use of rack cabinets.

The horizontal mounting means that the user normally cannot access the tape path to load the tape manually. Hence, an autoloading feature was designed into the HP 7980A. The operator simply places the tape reel in the door opening and closes the door. The autoloading sequence starts automatically once the door is closed, leaving the operator free to do other tasks while waiting for the tape to load nominal time of half a minute. There is no need for an EZ-LOAD cartridge around the tape reel, which is required for autoloading on the HP 7976A Tape Drive. The HP 7976A autoloads only 10.5-inch tape reels; the HP 7980A autoloads all standard half-inch tape reels from six to 10.5 inches in diameter. The earlier HP 7978A/B Tape Drive must be loaded manually and cannot autoload tapes.

In addition, the HP 7980A supports the use of 3600-foot half-inch tape, under certain guidelines, which the HP 7978B doesn't. This increase data capacity by 50 percent over standard-length tape reels.

The HP 7980A was developed and released in 40 percent less time than the previous tape drive. This was mainly a result of two factors. The first was keeping together an experienced core group of engineers from the HP 7978A/B development team to architect and design the HP 7980A drive. The second was concentrating on a core system development of the HP 7980A, that is, having a well-defined product and not adding additional features and configurations along the way. Such added features tend to prolong development cycles. This does not mean that these additional features are not eventually added, but they are worked on according to need after the core or base system is released.

Tape Path

The HP 7980A is a totally integrated tape drive, simultaneously incorporating a small form factor, an autoload feature, design-for-assembly concepts, low cost, and high reliability. The major design objective established to accomplish these goals was design simplication.

The HP 7980A has a very simple tape path as shown in Fig. 2. There are only two rolling elements: the speed sensor and teh buffer arm roller. There is only one additional fixed tape guide. The oxide side of the tape contacts only the tape cleaner, the magnetic tape head, and the tape displacement unit. The tape displacement unit, located between the tape head and the tape cleaner, contacts the oxide side of the tape only during respositioning and while the tape is stopped. The tape displacement unit pushes the tape off the very smooth surfaces of the head and the tape cleaner to prevent the tape's sticking to these smooth surfaces during high temperature and humidity conditions.

The buffer arm assembly (buffer arm, spring, and roller) helps take up slack in the tape during servo starts and stops. It also establishes the tension on the tape. The buffer arm roller and fixed guide, along with the speed sensor, guide the tape in a precise manner over the head. The speed sensor measures the velocity of the tape and feeds it back to the servo system.

The half-inch tape reel is centered, seated, and locked by the supply hub. The autoload blower forces air through the door. The louvers in the door direct the air onto the tape reel to lift the end of the tape. The tape end is then carried by the air flow around the buffer arm roller and the fixed guide. If then goes over the tape cleaner and the magnetic tape head. The tape is finally sucked onto the take-up reel after passing around the speed sensor.j

The drive motors are located directly beneath and are attached to the supply and take-up hubs. The blower is located between the two drive motors.

# posted by Medical Information : 6:11 AM