Random-Access Disk File Reduces Access Time

A new, random-access disk memory, the Telex I from Telex Inc., Minneapolis, has nearly a third the access time and double the storage capacity of currently available disk files. The improvement in access time is due to the two sets of read-record heads for each of the 16 stacked disks. Capacity is 20 to 22 million 7-bit characters per stack of disks. Competitive units have capacities of 10 million characters per stack. Average access time is 150 msec, and 250 msec maximum; that of competitive units is 425 msec average and 800 msec max.

The increased capacity is due primarily to the larger diameter of the Telex disks—31 in. compared with the conventional 24 in. Data are recorded on Telex with a density of 400 bits per inch of recording track.

As with competitive models, the Telex disks are mounted on a vertical shaft driven by a motor at 1200 rpm. The two heads are mounted about 5 in. apart on rigid arms, which move radially across a disk. The Telex I is set for production early next year and will be priced from $50,000 to $90,000. (electronic design, Aug. 17, 1960, p. 32)

Sixteen disks, each with a 31-in. diameter—quite a package for about 19 megabytes of storage.—Steve Scrupski