Fig. 1.7.2 Magnetic tape.

Disk Storage

The limitations of the magnetic tape file were such that soon there was an alternative
medium. That alternative medium was called disk storage (or direct access storage).
Direct access storage held the great advantage that data could be accessed directly. No
longer was it necessary to read an entire file in order to access just one record. With disk
storage, it was possible to go directly to a unit of data.

Fig. 1.7.3 shows disk storage.

Fig. 1.7.3 Disk storage.

At first, disk storage was expensive, and there wasn’t all that much capacity that was
available. But the hardware vendors quickly improved on the speed, the capacity, and the
cost of disk storage. And the improvements have continued until today.

Data Base Management System (DBMS)

Along with the advent of disk storage came the appearance of the database management
system (DBMS). The database management system controlled the placement, access,
update, and deletion of data on disk storage. The DBMS saved the programmer from
doing repetitive and complex work.

With the appearance of the DBMS came the ability to tie processors to the database (and

Chapter 1.7: A Brief History of Data