The B5000

Part of notes for CS:4980:4, Fall 2015
by Douglas W. Jones
THE UNIVERSITY OF IOWA Department of Computer Science

William Seward Burroughs developed the first successful bank adding machine, and went into production in 1888. His firm had a near monopoly on banking machines -- mechanical and electromechanical equipment specifically designed to meet the needs of bank record keeping and accounting. Slip the customer's bank book into the machiine, key in the previous balance (from the book), key in the quarterly interest rate, key in the date of the previous transaction (from the book) and pull the lever once for each quarter since the last transaction, and the machine will post the interest to the book. Then key in the current transaction, and pull the lever again, and it will post the updated balance to the book. These machines were big, expensive, and essential. Many small community banks continued using these machines into the 1970s (I recall having a savings account when I was in grad school that was updated this way).

But, Burroughs corporation understood the possibilities of the new era of electronic computing, and starting in the 1950s, they began to build electronic banking machines. Some of these were special purpose machines that were not that different from their earlier banking machines, but they also explored general purpose computers.

the B 5000, introduced in 1961-62, was with little question, the single most innovative new computer architecture of the era. This was a transistorized machine that had nothing to do with its predecessors. They did not even describe the assembly language to their customers, but instead, used a dialect of Algol 60 as their programming language. Even the operating system was written in a somewhat more specialized Algol dialect (they called it Algol S, if I recall correctly).

the B5000 was the founding member of a family that ended up including the B5500 and several more, with production continuing at least into the late 1970s. While different members of this family were not object-code compatable, all inherited the basic design, including pure stack-oriented instruction execution.