Burroughs B2000

The Burroughs B2000 series of computers was manufactured by Burroughs Corporation in Pasadena, California, United States, and was aimed straight at the business world. The architecture was built to support COBOL programming in the most efficient way possible, it was designed to narrow the semantic gap between high level languages and the hardware these programs executed on. The instruction set provided for 3 register operation allowing the COBOL operation ADD A, B GIVING C to be directly translated into a single machine instruction, this simplicity encouraged many customers to program their systems in assembler rather than a high-level language. This approach went to the lengths of providing single machine operation codes for "translate this buffer through this (e.g. EBCDIC to ASCII) conversion table into that buffer" or "sort this table using these sort requirements into that table", extreme instances of which were capable of running for several hundredths of a second.

The B2000-B4000 computers (known at the time as the Medium Systems Family) did everything in binary-coded decimal (BCD) arithmetic. Memory was addressed on decimal rather than the traditional binary boundaries, i.e. a block of storage (implemented as magnetic core or semiconductor RAM) provided 1000 words rather than 1024. Older members of the range, i.e. before the B2900, implemented undocumented 'un-digit' (hexadecimal) arithmetic, this was used by some application programmers and could also be found in the operating system. Later versions (B2900-B4900 series) discontinued this and instead supported two new opcodes (binary to decimal and decimal to binary) to support addressing the hard drives available after Burroughs's acquisition of Memorex.

The B2000-B4000 series were very effective multi-programming machines. Even very basic versions of the B2000 could support multi-programming on a usable scale. Larger Medium Systems processors supported major data center activities for banks and other financial institutions, as well as many businesses and government customers. The Medium System was the preferred platform for many data processing professionals.

With the Medium System, a computer could be simultaneously running a batch payroll system, inputting checks on an MICR reader sorter, compiling COBOL applications, supporting on-line transactions, and doing test runs on new applications. It was not unusual to be running eight or ten programs on a medium-size B2500. In addition, the operating system allowed programs to communicate with each other via core-to-core transmissions (CRCR) or by using storage queues (STOQ). This was unheard of except on the very largest IBM S/360 systems of the time, and even then it was a major operational headache to manage the interactions of the multiple program streams.

Medium System installations often had tape clusters (four drives integrated into a mid-height cabinet) 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 on these computers, but it was often not used for father-son batch updating but instead as a library/backup device that contained all the data files and sometimes the program files for a particular application or customer/client.

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

—a blank verse by unknown B2000 user