【NEC】 N7651 Mass Data File System

In October 1979, NEC announced the N7651 mass data file system which could hold a max.imum of 4720 data cartridges, for a max.imum capacity of 236GB.

This was an automatic library system for magnetic tape which used a new magnetic tape media to enable configuration of hierarchical high-speed, high-capacity file systems combining the features of two types of media: high-speed, multi-file, random access magnetic disk and low-speed, high-capacity magnetic tape.
In a complete system, this unit was combined with a magnetic disk unit, so that data requiring high-speed/frequent access was stored on the magnetic disk, while low-frequency data was stored on the mass data file system.

To facilitate automatic operation, this system used "data cartridges" which housed magnetic tape about 7cm wide and about 20m long in a cylindrical plastic cartridge. Data recording was done using a rotating head. One data cartridge had 13544 "stripes", and a total memory capacity of approximately 50MB. Using this system it was possible to escape from the "one file only" and "sequential file only" access constraints which were the weak point of magnetic tape.
Reading and writing were performed by using an automatic robot mechanism to move data cartridges requested by the host from the library section (which housed a few hundred to a few thousand data cartridges) to the read/write unit (data recording mechanism).

The N7651 mass data file system came in 4 models, depending on the number of stored data cartridges and the number of data recording mechanisms. In a main frame system, two N7651 systems could be handled as a single mass data file system.

The predecessor of this system (the N7650 Model 2) was introduced by Tsukuba University and began operations in March 1978, prior to the announcement of this product.