IBM RAMAC

One IBM RAMAC weighed nearly a ton (971 kg) and was leased at the price of 35,000 dollars a year. Actually, it is cost there are 17 new cars. For transportation of such winchester is more often than this small cargo airliners were used.

The drive consists of two huge blocks which occupy the space of 3 × 3.5 meters. Directly 50 disks from aluminum on which working surfaces the magnetic layer is applied are got on an axis of a powerful electric motor. Each disk has  diameter about 60 cm at  a thickness of 2.5 cm. All this large object rotates in an operating mode at constant angular velocity of 1200 RPM. On a surface of each disk, in a 5-inch external zone, 100 concentric tracks are located. For record and data reading the same methods which were applied in drives on magnetic tapes were used. On each track it was possible to remember 500 alphanumeric characters coded in the 7-bit code used then. And all RAMAC 305 could store 5  million characters.

The punched card metaphor was applied to a format of the sector if you had enough saw like that or you know, what is it. The average time of access to RAMAC was 600 ms, and data transfer rate  — to 9 KB/ss. Not such weak indicators. For internal use and experiments in IBM 14 devices  — prototypes of RAMAC were created. And the first industrial device was installed in June, 1956 by request of paper-making company Zellerbach Paper from San Francisco. On today's estimations made in IBM in 1956 the cost of one RAMAC device could be 50 thousand dollars that gives the specific cost of memory 11.364 dollars on megabyte. Production RAMAC stopped only in 1961. For these years 1.067 drives which were used on a first line of science, production, defense of the USA were released.