Pegasus: The Seminal Early computer

Hugh McGregor Ross et al

Published by

Bright Pen





Reviewed by



8 out of 10

You may not be interested in vintage computers, but when you are allowed to peep inside the cabinets, it’s difficult not to marvel at the engineering ingenuity and also at the many features which, to this day are still found in computers.

 That is exactly what this book does, and in three main sections -

  • a description of the metamorphosis of the Ferranti Pegasus during the 1950s from the Elliott 401;
  • the development of some of the pioneering concepts of hardware architecture and software design, which were used in the building of Pegasus;
  • and ending with a look at some of the descendants of Pegasus, including machines such as the ICT/ICL 1900.

Written by a member of the Ferranti team, there are also contributions from some of the key designers including a wonderfully concise eight-page technical specification of the Pegasus.

Some of the innovations that were incorporated into Pegasus included: accumulators and modifiers, parity bits and odd-parity self-checking, mixed radices, the package concept of machine design, a standard interface for peripheral devices and the use of an applications library.

The book would have benefited from an index and the formal style contrasts with the more chatty storybook style of Georgina Ferry’s excellent A computer called LEO.

Only some 40 Pegasus machines were sold between 1956-1962, and Ian Merry’s contribution in the last Appendix and indeed the last paragraph of the book sums up Pegasus perfectly: ‘The history of Pegasus has always seemed to be a paradigm of the British industrial malady - not just the shibboleth that Britain fails to market its wares, but more fundamentally that we no longer recognize or foster and therefore we cannot exploit our real strengths.’

The book fits nicely in bridging computer development between Colossus and the ‘Manchester’ machines of the 40s and early 50s, and the more classical mainframe computers of the 60s and 70s, such as the IBM 360 and the epic ICT/ICL 1900 series.

Good value at £10, and a documentary reminder of the golden age of British pioneering computer development.

November 2012