VAX (an acronym for virtual address extension) is a series of computers featuring a 32-bit instruction set architecture (ISA) and virtual memory that was developed and sold by Digital Equipment Corporation (DEC) in the late 20th century. The VAX-11/780, introduced October 25, 1977, was the first of a range of popular and influential computers implementing the VAX ISA. The VAX family was a huge success for DEC, with the last members arriving in the early 1990s. The VAX was succeeded by the DEC Alpha, which included several features from VAX machines to make porting from the VAX easier.
Key facts
- CPU architecture.name
- VAX
- CPU architecture.image
- VAX logo.svg
- CPU architecture.designer
- Digital Equipment Corporation
- CPU architecture.bits
- 32-bit
- CPU architecture.design
- CISC
- CPU architecture.encoding
- Variable (1 to 56 bytes)
- CPU architecture.endianness
- Little
- CPU architecture.extensions
- PDP-11 compatibility mode, VAX Vector Extensions, VAX Virtualization Extensions
- CPU architecture.open
- No
- CPU architecture.branching
- Condition code
- CPU architecture.page size
- 512 bytes
- CPU architecture.predecessor
- PDP-11
- CPU architecture.successor
- Alpha
- CPU architecture.gpr
- 16 × 32-bit
- CPU architecture.fpr
- not present, uses the GPR
- CPU architecture.vpr
- 16 × 4096-bit (64 elements of 64 bits each)
via Wikipedia infobox
Article
16 sectionsContents
- Description
- Name
- Instruction set
- Operating systems
- History
- Processor architecture
- Virtual memory map
- Privilege modes
- Processor status longword
- VAX-based systems
- SIMACS
- Canceled systems
- Clones
- References
- Further reading
- External links
VAX (an acronym for virtual address extension) is a series of computers featuring a 32-bit instruction set architecture (ISA) and virtual memory that was developed and sold by Digital Equipment Corporation (DEC) in the late 20th century. The VAX-11/780, introduced October 25, 1977, was the first of a range of popular and influential computers implementing the VAX ISA. The VAX family was a huge success for DEC, with the last members arriving in the early 1990s. The VAX was succeeded by the DEC Alpha, which included several features from VAX machines to make porting from the VAX easier.
==Description== VAX was designed by Digital Equipment Corporation (DEC) as a successor to the 16-bit PDP-11, one of the most successful minicomputers in history with approximately 600,000 units sold. The system was designed to offer backward compatibility with the PDP-11 while extending the memory to a full 32-bit implementation and adding demand paged virtual memory. The name VAX refers to its virtual address extension concept that allowed programs to make use of this newly available memory while still being compatible with unmodified user mode PDP-11 code. The name "VAX-11", used on early models, was chosen to highlight this capability. The VAX ISA is considered a complex instruction set computer (CISC) design.