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The Burroughs B2000 series of machines was manufactured by Burroughs Corporation in Pasadena, California and was aimed straight at the business world. The architecture was built to support COBOL programming in the most efficient way possible. the B2000 architecture was designed to narrow the semantic gap between high level languages and the hardware these programs executed on.

The B2000-B4000 machines (known at the time as the Medium Systems Family) did everything in binary-coded decimal (BCD) arithmetic. Memory was addressed on BCD boundaries instead of the traditional binary boundaries. The architecture featured an instruction code set that provided for 3 register operation allowing the COBOL operation ADD A, B giving C to be directly translated into a single machine instruction. Later versions (B2900-B4900 series) supported two new opcodes (binary to decimal/decimal to binary) to support addressing of the Memorex hard drives.

The B2000-B4000 series were very effective multi-programming machines. Even very basic versions of the B2000 could support multi-programming on a useable scale. Larger B-series processors supported major data center activities for banks and other financial institutions, as well as many businesses and government customers. The B-series was the preferred platform for many data processing professionals. Although these machines were not as reliable as the IBM 360-series machines, they were so much more flexible and easy to program, that many hard core programmers and most operations personnel loved them. With the B-series, a machine could be simultaneously running a batch payroll system, inputting checks on an MICR reader sorter, compiling COBOL applications, and doing test runs on new applications. It was not unusual to be running eight or ten programs on a medium-size B2500. This was unheard of except on the very largest 360 systems, and even then it was a major operational headache to manage the interactions of the multiple program streams.

The B-series systems often had tape clusters for magnetic tape input and output. Free-standing tape drives were also available, but they were much more expensive. Tape was a major storage medium for the B-series, but it was often not used for father-son batch updating, instead the mag tape was used as a library/backup device that contained all the data files and sometimes the program files for a particular application or customer/client.

c:/jeff/burroughs tape cluster.jpg

COBOL to machine code
Tape resident disk files
Job headers for card input
Card and print spooling
I did accounting system (parameter driven)

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