Burroughs B1700

Last updated

The Burroughs B1000 Series was a series of mainframe computers, built by the Burroughs Corporation, and originally introduced in the 1970s with continued software development until 1987. The series consisted of three major generations which were the B1700, B1800, and B1900 series machines. They were also known as the Burroughs Small Systems, by contrast with the Burroughs Large Systems (B5000, B6000, B7000, B8000) and the Burroughs Medium Systems (B2000, B3000, B4000).

Contents

Much of the original research for the B1700, initially codenamed the PLP ("Proper Language Processor" or "Program Language Processor"), was done at the Burroughs Pasadena plant. [1]

Production of the B1700s began in the mid-1970s and occurred at both the Santa Barbara and Liège, Belgium plants. The majority of design work was done at Santa Barbara with the B1830 being the notable exception designed at Liège.

Features

Writeable control store

The B1000 is distinguished from other machines in that it had a writeable control store allowing the machine to emulate any other machine. The Burroughs MCP (Master Control Program) would schedule a particular job to run. The MCP would preload the interpreter for whatever language was required. These interpreters presented different virtual machines for COBOL, Fortran, etc.

A notable idea of the "semantic gap" between the ideal expression of the solution to a particular programming problem, and the real physical hardware illustrated the inefficiency of current machine implementations. The three Burroughs architectures represent solving this problem by building hardware aligned with high-level languages, so-called language-directed design (contemporary term; today more often called a "high-level language computer architecture"). The large systems were stack machines and very efficiently executed ALGOL. The medium systems (B2000, 3000, and B4000) were aimed at the business world and executing COBOL (thus everything was done with BCD including addressing memory.) The B1000 series was perhaps the only "universal" solution from this perspective because it used idealized virtual machines for any language.

The actual hardware was built to enhance this capability. Perhaps the most obvious examples were the bit-addressable memory, the variable size arithmetic logic unit (ALU), and the ability to OR in data from a register into the instruction register allowing very efficient instruction parsing. Another feature of the machine language was the appearance of having the output of the ALU appear as different addressable registers. X+Y, and X-Y are two read-only registers within the machine language.

Internals

One concession to the fact that Burroughs was primarily a supplier to business (and thus running COBOL) was the availability of BCD arithmetic in the ALU.

Internally, the machines employed 16-bit instructions and a 24-bit data path. The bit addressable memory supported the mix quite efficiently. Internally, the later generation memories stored data on 32-bit boundaries, but were capable of reading across this boundary and supplying a merged result.

The initial hardware implementations were built out of the Complementary Transistor Logic (CTL) Family originally made by Fairchild Semiconductor but with the introduction of the B1955 in 1979 the series employed the more popular (and more readily obtainable) TTL logic family. Up through the B1955, the control logic was implemented with PROMs, muxes and such.

The B1965, the last of the series, was implemented with a pair of microcode sequencers which stayed in lock step with each other. The majority of the instructions executed in a single cycle. This first cycle was decoded by FPLAs using 16 inputs (just the perfect size for a 16-bit instruction word) and 48 min-terms. Successive cycles from a multi-cycle instruction were sourced from PROMs. The FPLAs and PROM outputs were wired together. The FPLA would drive the output on the first cycle, then get tri-stated. The PROMs would drive the control lines until the completion of the instruction.

I/O

The I/O system for the B1000 series consisted of a 24-bit data path and control strobes to and from the peripherals. The CPU would place data on the data path, then inform the peripheral that data was present. Many of the peripheral adapters were fairly simplistic, and the CPU actually drove the adapter state machines through their operations with successive accesses.

Later models of the machines in both the 1800 and 1900 series could be configured as either a single or dual processor. These were tightly coupled machines and competed in access to the main memory. The B1955 and B1965 could accommodate up to four processors on the memory bus, but at least one of these would be assigned to the Multi-Line adapter which supplied serial I/O to the system. Only Dual-processor configurations were ever actually sold.

The Multi-Line was capable of driving multiple 19.2Kb RS485 serial lines in a multi-drop configuration. The serial I/O was polled. A given terminal would wait until it was addressed, and grab the line and send any data it had pending.

The Multi-Line Adapter would DMA the data into main memory in a linked list format. Consequently, the processors didn't have to deal with serial I/O interrupt issues. This was taken care of by the fact that block mode terminals were the only type supported.

The B1000 series could address a maximum of 2 megabytes of memory. In these days of multiple gigabytes that sounds fairly limiting, but most commercial installations got by with hundreds of kilobytes of storage.

Notes

  1. ETM 313: Proper Language Processor for Small Systems (Bunker, et al.), 1968.

Related Research Articles

<span class="mw-page-title-main">Burroughs Corporation</span> American computer company

The Burroughs Corporation was a major American manufacturer of business equipment. The company was founded in 1886 as the American Arithmometer Company by William Seward Burroughs. In 1986, it merged with Sperry UNIVAC to form Unisys. The company's history paralleled many of the major developments in computing. At its start, it produced mechanical adding machines, and later moved into programmable ledgers and then computers. It was one of the largest producers of mainframe computers in the world, also producing related equipment including typewriters and printers.

<span class="mw-page-title-main">Central processing unit</span> Central computer component which executes instructions

A central processing unit (CPU), also called a central processor, main processor, or just processor, is the most important processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, logic, controlling, and input/output (I/O) operations. This role contrasts with that of external components, such as main memory and I/O circuitry, and specialized coprocessors such as graphics processing units (GPUs).

In processor design, microcode serves as an intermediary layer situated between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer, also known as its machine code. It consists of a set of hardware-level instructions that implement the higher-level machine code instructions or control internal finite-state machine sequencing in many digital processing components. While microcode is utilized in general-purpose CPUs in contemporary desktops, it also functions as a fallback path for scenarios that the faster hardwired control unit is unable to manage.

<span class="mw-page-title-main">Motorola 68020</span> 32-bit microprocessor

The Motorola 68020 is a 32-bit microprocessor from Motorola, released in 1984. A lower-cost version was also made available, known as the 68EC020. In keeping with naming practices common to Motorola designs, the 68020 is usually referred to as the "020", pronounced "oh-two-oh" or "oh-twenty".

<span class="mw-page-title-main">IBM 1620</span> Small IBM scientific computer released in 1959

The IBM 1620 was announced by IBM on October 21, 1959, and marketed as an inexpensive scientific computer. After a total production of about two thousand machines, it was withdrawn on November 19, 1970. Modified versions of the 1620 were used as the CPU of the IBM 1710 and IBM 1720 Industrial Process Control Systems.

<span class="mw-page-title-main">UNIVAC</span> Series of mainframe computer models

UNIVAC was a line of electronic digital stored-program computers starting with the products of the Eckert–Mauchly Computer Corporation. Later the name was applied to a division of the Remington Rand company and successor organizations.

Tandem Computers, Inc. was the dominant manufacturer of fault-tolerant computer systems for ATM networks, banks, stock exchanges, telephone switching centers, 911 systems, and other similar commercial transaction processing applications requiring maximum uptime and zero data loss. The company was founded by Jimmy Treybig in 1974 in Cupertino, California. It remained independent until 1997, when it became a server division within Compaq. It is now a server division within Hewlett Packard Enterprise, following Hewlett-Packard's acquisition of Compaq and the split of Hewlett-Packard into HP Inc. and Hewlett Packard Enterprise.

The Burroughs Large Systems Group produced a family of large 48-bit mainframes using stack machine instruction sets with dense syllables. The first machine in the family was the B5000 in 1961, which was optimized for compiling ALGOL 60 programs extremely well, using single-pass compilers. The B5000 evolved into the B5500 and the B5700. Subsequent major redesigns include the B6500/B6700 line and its successors, as well as the separate B8500 line.

In computer science, computer engineering and programming language implementations, a stack machine is a computer processor or a virtual machine in which the primary interaction is moving short-lived temporary values to and from a push down stack. In the case of a hardware processor, a hardware stack is used. The use of a stack significantly reduces the required number of processor registers. Stack machines extend push-down automata with additional load/store operations or multiple stacks and hence are Turing-complete.

<span class="mw-page-title-main">Microarchitecture</span> Component of computer engineering

In electronics, computer science and computer engineering, microarchitecture, also called computer organization and sometimes abbreviated as µarch or uarch, is the way a given instruction set architecture (ISA) is implemented in a particular processor. A given ISA may be implemented with different microarchitectures; implementations may vary due to different goals of a given design or due to shifts in technology.

The Burroughs B2500 through Burroughs B4900 was a series of mainframe computers developed and manufactured by Burroughs Corporation in Pasadena, California, United States, from 1966 to 1991. They were aimed at the business world with an instruction set optimized for the COBOL programming language. They were also known as Burroughs Medium Systems, by contrast with the Burroughs Large Systems and Burroughs Small Systems.

PicoBlaze is the designation of a series of three free soft processor cores from Xilinx for use in their FPGA and CPLD products. They are based on an 8-bit RISC architecture and can reach speeds up to 100 MIPS on the Virtex 4 FPGA's family. The processors have an 8-bit address and data port for access to a wide range of peripherals. The license of the cores allows their free use, albeit only on Xilinx devices, and they come with development tools. Third-party tools are available from Mediatronix and others. Also PacoBlaze, a behavioral and device independent implementation of the cores exists and is released under the BSD License. The PauloBlaze is an open source VHDL implementation under the Apache License.

The Orion was a series of 32-bit super-minicomputers designed and produced in the 1980s by High Level Hardware Limited (HLH), a company based in Oxford, UK. The company produced four versions of the machine:

<span class="mw-page-title-main">AMD Am2900</span>

Am2900 is a family of integrated circuits (ICs) created in 1975 by Advanced Micro Devices (AMD). They were constructed with bipolar devices, in a bit-slice topology, and were designed to be used as modular components each representing a different aspect of a computer control unit (CCU). By using the bit slicing technique, the Am2900 family was able to implement a CCU with data, addresses, and instructions to be any multiple of 4 bits by multiplying the number of ICs. One major problem with this modular technique was that it required a larger number of ICs to implement what could be done on a single CPU IC. The Am2901 chip included an arithmetic logic unit (ALU) and 16 4-bit processor register slices, and was the "core" of the series. It could count using 4 bits and implement binary operations as well as various bit-shifting operations. The Am2909 was a 4-bit-slice address sequencer that could generate 4-bit addresses on a single chip, and by using n of them, it was able to generate 4n-bit addresses. It had a stack that could store a microprogram counter up to 4 nest levels, as well as a stack pointer.

<span class="mw-page-title-main">History of general-purpose CPUs</span>

The history of general-purpose CPUs is a continuation of the earlier history of computing hardware.

<span class="mw-page-title-main">VAX 8000</span> Family of superminicomputers by Digital Equipment Corporation

The VAX 8000 is a discontinued family of superminicomputers developed and manufactured by Digital Equipment Corporation (DEC) using processors implementing the VAX instruction set architecture (ISA).

<span class="mw-page-title-main">60-bit computing</span>

In computer architecture, 60-bit integers, memory addresses, or other data units are those that are 60 bits wide. Also, 60-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers, address buses, or data buses of that size.

<span class="mw-page-title-main">1-bit computing</span> Computer architecture bit width

In computer architecture, 1-bit integers or other data units are those that are 1 bit wide. Also, 1-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers of that size.

The Hack Computer is a theoretical computer design created by Noam Nisan and Shimon Schocken and described in their book, The Elements of Computing Systems: Building a Modern Computer from First Principles.  In using the term “modern”, the authors refer to a digital, binary machine that is patterned according to the von Neumann architecture model.

The MAC-8, better known today as the BELLMAC-8, is an 8-bit microprocessor designed by Bell Labs. Production began in CMOS form at Western Electric as the WE212 in 1977. The MAC-8 was used only in AT&T products, like the 4ESS. No commercial spec sheets were published, so it is little known as a result. The best-known use, in the public, is the MAC-TUTOR computer trainer, released in 1979.

References