R2000 (microprocessor)
Encyclopedia
The R2000 is a microprocessor
chip set developed by MIPS Computer Systems that implemented the MIPS I instruction set architecture (ISA). Introduced in January 1986, it was the first commercial implementation of the MIPS architecture and the first merchant RISC processor available to all companies. The R2000 competed with Digital Equipment Corporation
(DEC) VAX
minicomputers and with Motorola
68000 and Intel Corporation
80386 microprocessors. R2000 users included Ardent Computer
, DEC, Silicon Graphics
, and MIPS's own Unix workstations.
The chip set consisted of the R2000 microprocessor, R2010 floating-point accelerator, and four R2020 write buffer chips. The core R2000 chip executed all non-floating-point instructions with a simple short pipeline. This chip also controlled the external code and data caches, made of fast standard SRAM chips organized with direct indexing and one-cycle read latency. The R2000 chip contained a small translation lookaside buffer
for mapping virtual memory addresses. The R2010 chip held the floating point registers, floating point data paths, and their longer simple pipeline. Writes to main memory DRAM took tens of cycles to fully complete. But the R2020 chips queued and completed up to 4 pending writes to main memory, allowing the R2000 core to proceed without stalling itself. In the absence of cache misses, this chip set sustained an instruction completion rate of one instruction per ALU cycle. This was much faster than non-RISC microprocessors of that time which needed several cycles per instruction. 1986 also saw similar technology in Sun's first SPARC
microprocessor and Hewlett Packard's first PA-RISC
microprocessor.
Overall speed was limited by the cache size and cache cycle time. The R2000 chip set and SRAM was initially sold only as a complete circuit board to ensure good cache bus timings. In 1987 system builders began using the chip set in arbitrary new board designs.
The R2000 was available in 8.3, 12.5 and 15 MHz grades. The die contained 110,000 transistors and measured 80 mm2 in a 2.0 μm double-metal CMOS process. MIPS was a fabless semiconductor company, that is, they did not have the capability to fabricate integrated circuits. The chip set was initially fabricated for MIPS by Sierra Semiconductor and Toshiba
. In December 1987, MIPS licensed Integrated Device Technology
, LSI Logic, and Performance Semiconductor to also fabricate and market the R2000. Sierra and Toshiba continued to serve as foundries.
LSI fabricated the chip set in its 2.0 μm double-metal CMOS process and marketed it as the LR2000. Performance Semiconductor fabricated the chip set in its PACE-I 0.8 μm double-metal CMOS process and marketed it as the PR2000.
In 1988, an improved version was introduced, the R2000A. It was composed of the R2000A and R2010A ICs. It operated at 12.5 and 16.67 MHz. It has been used extensively in embedded applications such as printer controllers.
In 1988, the R2000 was followed by the R3000
, using a similar overall system design but faster chip implementation.
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
chip set developed by MIPS Computer Systems that implemented the MIPS I instruction set architecture (ISA). Introduced in January 1986, it was the first commercial implementation of the MIPS architecture and the first merchant RISC processor available to all companies. The R2000 competed with Digital Equipment Corporation
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
(DEC) VAX
VAX
VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs...
minicomputers and with Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
68000 and Intel Corporation
Intel Corporation
Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...
80386 microprocessors. R2000 users included Ardent Computer
Ardent Computer
The Ardent Computer Corporation was a graphics minicomputer manufacturing company. The systems also used the Intel i860 as graphics co-processors. The company went through a series of mergers and re-organizations and changed names several times as their venture capital funders attempted to find a...
, DEC, Silicon Graphics
Silicon Graphics
Silicon Graphics, Inc. was a manufacturer of high-performance computing solutions, including computer hardware and software, founded in 1981 by Jim Clark...
, and MIPS's own Unix workstations.
The chip set consisted of the R2000 microprocessor, R2010 floating-point accelerator, and four R2020 write buffer chips. The core R2000 chip executed all non-floating-point instructions with a simple short pipeline. This chip also controlled the external code and data caches, made of fast standard SRAM chips organized with direct indexing and one-cycle read latency. The R2000 chip contained a small translation lookaside buffer
Translation Lookaside Buffer
A translation lookaside buffer is a CPU cache that memory management hardware uses to improve virtual address translation speed. All current desktop and server processors use a TLB to map virtual and physical address spaces, and it is ubiquitous in any hardware which utilizes virtual memory.The...
for mapping virtual memory addresses. The R2010 chip held the floating point registers, floating point data paths, and their longer simple pipeline. Writes to main memory DRAM took tens of cycles to fully complete. But the R2020 chips queued and completed up to 4 pending writes to main memory, allowing the R2000 core to proceed without stalling itself. In the absence of cache misses, this chip set sustained an instruction completion rate of one instruction per ALU cycle. This was much faster than non-RISC microprocessors of that time which needed several cycles per instruction. 1986 also saw similar technology in Sun's first SPARC
SPARC
SPARC is a RISC instruction set architecture developed by Sun Microsystems and introduced in mid-1987....
microprocessor and Hewlett Packard's first PA-RISC
PA-RISC
PA-RISC is an instruction set architecture developed by Hewlett-Packard. As the name implies, it is a reduced instruction set computer architecture, where the PA stands for Precision Architecture...
microprocessor.
Overall speed was limited by the cache size and cache cycle time. The R2000 chip set and SRAM was initially sold only as a complete circuit board to ensure good cache bus timings. In 1987 system builders began using the chip set in arbitrary new board designs.
The R2000 was available in 8.3, 12.5 and 15 MHz grades. The die contained 110,000 transistors and measured 80 mm2 in a 2.0 μm double-metal CMOS process. MIPS was a fabless semiconductor company, that is, they did not have the capability to fabricate integrated circuits. The chip set was initially fabricated for MIPS by Sierra Semiconductor and Toshiba
Toshiba
is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...
. In December 1987, MIPS licensed Integrated Device Technology
Integrated Device Technology
Integrated Device Technology, Inc. is a publicly traded corporation headquartered in San Jose, California, that designs, manufactures, and markets low-power, high-performance mixed-signal semiconductor solutions for the advanced communications, computing, and consumer industries. The company...
, LSI Logic, and Performance Semiconductor to also fabricate and market the R2000. Sierra and Toshiba continued to serve as foundries.
LSI fabricated the chip set in its 2.0 μm double-metal CMOS process and marketed it as the LR2000. Performance Semiconductor fabricated the chip set in its PACE-I 0.8 μm double-metal CMOS process and marketed it as the PR2000.
In 1988, an improved version was introduced, the R2000A. It was composed of the R2000A and R2010A ICs. It operated at 12.5 and 16.67 MHz. It has been used extensively in embedded applications such as printer controllers.
In 1988, the R2000 was followed by the R3000
R3000
The R3000 is a microprocessor chip set developed by MIPS Computer Systems that implemented the MIPS I instruction set architecture . Introduced in June 1988, it was the second MIPS implementation, succeeding the R2000 as the flagship MIPS microprocessor...
, using a similar overall system design but faster chip implementation.