Storage Hierarchies
Storage hierarchies have existed for as long as stored program
computers themselves. The Ferranti Mark 1 installed at Manchester
University in February 1951 had a main store made up of eight Williams
Tubes each containing 32 40-bit words and a drum backing store having
a capacity of 3.75 Kwords. Initially users were required to organise
their own store transfers between a selected drum track and a selected
pair of Williams Tubes, but the Mark 1 Autocode system introduced in
1954 carried out these tasks automatically on behalf of users and so
made the two levels of storage appear to them as a one-level store.
This arrangement was possible because the Mark 1 was a single user
machine, and its performance was acceptable because the time required
to transfer one drum track was roughly the same as the time for a
programmed floating-point addition. Later developments in both
architecture and technology led to the need for more sophisticated
systems and a variety of techniques has been developed.
Contents:
Return to Title Page