Classic Computer Magazine Archive COMPUTE! ISSUE 25 / JUNE 1982 / PAGE 107

Hardbox For PET/CBM

Richard Mansfield
Assistant Editor

The old distinctions between "big" and "small," between mini- and microcomputers, keep breaking down. What would you call a PET with 80 mega-bytes (80 million bytes) of memory? It is possible to attach as many as four Corvus hard disk units with up to 20 megabytes each to a PET by using Small Systems Engineering's new Hardbox.

A typical setup would involve attaching the cable (which normally goes between your computer and a floppy disk drive) to the Hardbox instead. The unit is about as big as a medium-sized portable radio and connects directly to a Corvus hard disk drive. It acts as an intelligent controller and can handle up to four hard drives – hence, 80 megabytes.

It takes very little getting used to: the software is compatible with both PET/CBM DOS versions one and two so it will work with floppy files and existing programs. The manufacturer states that it "is designed to appear to the PET as a fast, high-capacity floppy disk unit" and that's what it does. Even the "wedge" is allowed. To scratch a file, for example, you could use either sC"name" or PRINT#1,"S0:filename" – the two, familiar DOS grammars. The Hardbox comes with a collection of utility programs for diagnostics, formatting, backup, and so on. The only unsupported DOS commands are memory-read, -write, and. execute.

Data transfer is fast. Drive access time for ten or 20 megabyte drives is 40ms average and a five megabyte drive is 125ms average. The maximum record size is 255 bytes in relative files, the maximum number of records is 65535, and the maximum file size is 16 megabytes, either sequential or relative. On a five megabyte drive, more than 2000 files can be created with 13 open per Hardbox at any one time.

There is an issue to be resolved when using megabyte hard disks. How do you back them up? A 20 megabyte Corvus unit costs $5995. It may be impractical to buy a second unit to serve merely as backup. The solution? "Corvus Mirror" is supported by the Hardbox. An ordinary videocassette recorder can be attached as a backup device and it will copy the hard disk at a rate of 7.5K per second. A ten megabyte drive can be backed up in 20 minutes. Alternatively, a PET floppy drive or even a cassette unit could be used for backing up medium-size files.

Hardbox also supports multi-user environments. With an eight-way multiplexer, eight PETs can address the same hard disk at the same time, with individual and shared areas, passwords, and protected zones. Each Hardbox may be separated by up to 20 yards from the multiplexer and, with two levels of multiplexing, a maximum of 64 users can connect.

Small Systems Engineering
222B View St.
Mountain View, CA 94041