VAX

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VAX, (Virtual Address Extension) an instruction set architecture, developed by Digital Equipment Corporation (DEC) in the mid-1970s, to extend the PDP-11 architecture to a 32-bit orthogonal instruction set while adding a complete virtual memory system to the simple paging and memory protection of the PDP-11. The first computer to use a VAX CPU was the VAX-11/780, which DEC referred to as a Superminicomputer. DEC's VAX strategy was formulated by Gordon Bell.

=Registers= VAX has 16 32-bit registers, R0-R15. R0-R11 general purpose, R12/AP the argument pointer, R13/FP the frame pointer, R14/SP the stack pointer, and R15/PC the program counter or instruction pointer.

=Instructions= The general form of a VAX instruction ... opcode [ operand ] [ operand ] ... ... has each component being one byte, the opcode a value in the range 0 - 255, and each operand consisting of two nibbles, the upper 4 bits specifying an addressing mode, and the lower 4 bits (usually) a register number (R0 - R15). =MicroVAX= The MicroVAX was a family of low-end minicomputers implemented the VAX instruction set architecture, first introduced in 1984.

=Chess Programs= Category:VAX

=See also=
 * DEC Alpha
 * PDP-11
 * Virtual Memory

=External Links=
 * VAX from Wikipedia
 * List of VAX computers from Wikipedia
 * NVAX from Wikipedia
 * VAX-11 from Wikipedia
 * VAX 8000 from Wikipedia
 * VAX 7000/10000 from Wikipedia
 * VAXstation from Wikipedia
 * MicroVAX from Wikipedia
 * MicroVAX 78032 from Wikipedia
 * VAX Macro from Wikipedia
 * OpenVMS from Wikipedia

=References= Up one Level