HP 7935
| Company type | Product |
|---|---|
| Industry | Computer hardware |
| Founded | 1982 |
| Headquarters | Boise , United States |
| Products | Hard disk drive system |
The HP 7935 represents a business-oriented hard disk drive system produced by Hewlett Packard's Disc Memory Division located in Boise, Idaho, USA, beginning production in 1982 with an approximate price of $27,000. Internally referred to as the "BFD," which stands for "big fixed disc," this model was considerably larger compared to its predecessor, the 7920 series.
Size
Equipped with four casters at the base for ease of movement and four locking feet to ensure steadiness, the 7935's robust linear motor was capable of moving the unit if the feet were not properly engaged during use.
Its physical measurements are as follows: Height - 82.5 cm (32.5 inches), Width - 55.2 cm (21.7 inches), Depth - 83.4 cm (32.8 inches), and it weighs 154 kg (339.5 lb).
Media
The HP 7935 utilized a removable 404 megabyte model 97935 Disc Pack, facilitating versatile data handling. A closely related model, the HP7933, employed the same drive mechanism but featured a disc pack removable exclusively by service technicians.
Offering a threefold increase in storage capacity over the HP 7925 series at a marginally higher price point, the 793x family initially experienced a 15-20% decrease in performance. However, HP's subsequent Performance Enhancement Project boosted the 7935's throughput by approximately 15%, bringing it on par with earlier models.
Boasting a track density of 625 tracks per inch—a notably high figure for that period—the HP 7935/33 incorporated seven platters, thirteen data surfaces, and fourteen read/write heads, one of which was dedicated to servo positioning. The disc pack operated at a rotational speed of 2694 RPM.
Although it featured an advanced air purging spin-up process designed to minimize contamination risks, frequent user-caused disc head crash incidents led many users to favor the more maintenance-accessible HP 7933 variant.
Features
The 7935H included a rear-mounted HP-IB interface. Its front control panel comprised a keypad for conducting internal diagnostics, an LED character display, buttons for loading and unloading media, as well as a lid release mechanism.
A budget-friendly option called the 7935G combined three 7935H units into a single package offered at $74,000.
Use
Both the 7933 and 7935 drives were commonly integrated with the HP 3000 minicomputer line and early versions of the HP 9000 series. Utilizing the HP-IB interface allowed multiple drives to be connected in series, with device addresses configured via DIP switches adjacent to the interface port.
The robustness of these drives was demonstrated during the 1989 Loma Prieta earthquake at HP’s Cupertino facility, where out of 1,682 units tested immediately afterward, 97.25% remained fully functional. Within hours post-event, failure rates dropped to only about 2%, further decreasing to approximately 1.5% after several days.
As Hewlett-Packard transitioned toward compact, rack-mountable sealed drives employing Winchester technology—such as the HP 7963—the demand for the HP793x series gradually diminished.