Rigel (microprocessor)

DEC Rigel DC523 FPU die shot
DEC Rigel DC592 cache controller die shot

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 43 MHz.

The Rigel chipset consisted of several devices:

  • REX520 central processing unit (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 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.