Rigel (microprocessor)
Encyclopedia
Rigel was a microprocessor
chip set developed and fabricated by Digital Equipment Corporation
(DEC) that implemented the VAX
instruction set architecture (ISA). It was introduced on 11 July 1989 with the introduction of the VAX 6000 Model 400, the first system to feature the chip set. Rigel was also used in the VAX 4000
Model 300 and VAXstation
3100 Model 76. Production Rigel CPUs were rated at 35 to 40 MHz.
The Rigel chipset
consisted of several devices:
In addition, two further devices implemented the VAX vector processor
option; these comprised the DC555 Vector Register set chip (VERSE) and the DC556 Vector Data Path chip (FAVOR).
Support chips for Rigel-based systems included the RSSC (Rigel System Support Chip) and Ghidra, the VAX 4000 system interface chip.
processor. It has a six-stage microinstruction pipeline and 64-entry fully associative translation look-aside buffer. The Rigel chip set supported an optional vector processor
and the REX520 decoded any vector instructions and passed on to the vector interface (VC) chip by the REX520.
The REX520 has a 2 KB unified primary cache, configurable as an instruction cache and an external 128 KB secondary cache (backup cache) implemented with CMOS static random access memory
(SRAM) chips. The REX520 has an external cache because the VAX 8800's 64 KB primary cache could not be integrated on the same die. The backup cache controller was located on the VC chip.
The REX520 consisted of 320,000 transistors, of which 140,000 are for logic and 180,000 for memory. The die measures 12 mm by 12 mm (144 mm²). It was packaged in a 224-lead ceramic leaded package.
(CMOS) process, CMOS-2. The process had a 1.5 µm minimum feature size and two levels of aluminium interconnect.
3100 Model 80 and VAXstation 4000 Model 60.
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 and fabricated by 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) that implemented the 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...
instruction set architecture (ISA). It was introduced on 11 July 1989 with the introduction of the VAX 6000 Model 400, the first system to feature the chip set. Rigel was also used in the VAX 4000
VAX 4000
The VAX 4000 was a family of low-end minicomputers developed and manufactured by Digital Equipment Corporation using microprocessors implementing the VAX instruction set architecture . The VAX 4000 succeeded the MicroVAX family...
Model 300 and VAXstation
VAXstation
The VAXstation was a family of workstation computers developed and manufactured by Digital Equipment Corporation using processors implementing the VAX instruction set architecture .- VAXstation I :...
3100 Model 76. Production Rigel CPUs were rated at 35 to 40 MHz.
The Rigel chipset
Chipset
A chipset, PC chipset, or chip set refers to a group of integrated circuits, or chips, that are designed to work together. They are usually marketed as a single product.- Computers :...
consisted of several devices:
- REX520 central processing unitCentral processing unitThe central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
(also known as the DC520 or "P-chip") - DC523 floating-point unit (codenamed KIWI or "F-chip" during development)
- DC592 cache controller (codenamed COW or "C-chip" during development)
- DC521 clock chip
In addition, two further devices implemented the VAX vector processor
Vector processor
A vector processor, or array processor, is a central processing unit that implements an instruction set containing instructions that operate on one-dimensional arrays of data called vectors. This is in contrast to a scalar processor, whose instructions operate on single data items...
option; these comprised the DC555 Vector Register set chip (VERSE) and the DC556 Vector Data Path chip (FAVOR).
Support chips for Rigel-based systems included the RSSC (Rigel System Support Chip) and Ghidra, the VAX 4000 system interface chip.
REX520
The Rigel architecture was based on the VAX 8800VAX 8000
The VAX 8000 was a family of minicomputers developed and manufactured by Digital Equipment Corporation using processors implementing the VAX instruction set architecture .- VAX 8600 :...
processor. It has a six-stage microinstruction pipeline and 64-entry fully associative translation look-aside buffer. The Rigel chip set supported an optional vector processor
Vector processor
A vector processor, or array processor, is a central processing unit that implements an instruction set containing instructions that operate on one-dimensional arrays of data called vectors. This is in contrast to a scalar processor, whose instructions operate on single data items...
and the REX520 decoded any vector instructions and passed on to the vector interface (VC) chip by the REX520.
The REX520 has a 2 KB unified primary cache, configurable as an instruction cache and an external 128 KB secondary cache (backup cache) implemented with CMOS static random access memory
Static random access memory
Static random-access memory is a type of semiconductor memory where the word static indicates that, unlike dynamic RAM , it does not need to be periodically refreshed, as SRAM uses bistable latching circuitry to store each bit...
(SRAM) chips. The REX520 has an external cache because the VAX 8800's 64 KB primary cache could not be integrated on the same die. The backup cache controller was located on the VC chip.
The REX520 consisted of 320,000 transistors, of which 140,000 are for logic and 180,000 for memory. The die measures 12 mm by 12 mm (144 mm²). It was packaged in a 224-lead ceramic leaded package.
Fabrication
The chip set was fabricated by DEC in their second-generation complementary metal–oxide–semiconductorCMOS
Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...
(CMOS) process, CMOS-2. The process had a 1.5 µm minimum feature size and two levels of aluminium interconnect.
Mariah
Mariah was a revised version of the Rigel chip set fabricated by DEC in their 1 µm CMOS-3 process, with higher clock frequencies between 62 to 71 MHz. The Mariah CPU, FPU and cache controller were designated DC595, DC596 and DC597 respectively. Enhancements over Rigel included a 4 kB first-level cache and 32-bit physical memory addressing in the Mariah CPU, and write-back caching implemented in the cache controller chip. Mariah was used in the VAX 6000 Model 500, MicroVAXMicroVAX
The MicroVAX was a family of low-end minicomputers developed and manufactured by Digital Equipment Corporation . The first model, the MicroVAX I, was introduced in 1984...
3100 Model 80 and VAXstation 4000 Model 60.