An Algorithm for Swapping Data from Drum to Core

摘要

Because of its great cost, it is important to use a computer as efficiently as possible. Unfortunately, running programs frequently block due to some slower element of the system, as, for example, a card reader or a magnetic tape unit. Rather than permit the machine to sit idle in such instances, it is common practice to halt computation entirely for a period on the blocked program and initiate a new computation. Since the latter program may be also subject to blocking, it becomes reasonable to have available a small collection of programs among which the computer processes as determined by the blocking phenomenon and thus is kept continually busy. It is not economically feasible to equip such a machine with sufficient high - speed memory to hold the number of programs in such a set. Most of the programs must be kept in a secondary (and cheaper) memory and must be brought into high - speed memory at the appropriate time. The paper will consider the problem of managing the transfers of programs between the primary (core) and secondary (drum) memories of a system which has a moderate size core memory, a large drum, and a processor.