ARM2

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ARM2, (ARM3) the Acorn RISC Machine ARMv2 architecture is a 32-bit CMOS reduced instruction set computer, first released in 1987 as successor of the initial ARM (1985), designed by Sophie Wilson and Steve Furber in 1984. It features a 32-bit data bus, a 26-bit address space and sixteen 32-bit registers (r0 - r15, including PC and SP), and a 3-stage pipelined (Fetch, Decode, Execute) Von Neumann architecture. The ARM is a bi endian machine, per default little-endian. =Features= The ARM instruction set features three operand instructions, and conditional execution to avoid conditional branches. Some sample ARM assembly : CMP   r0, r1           ; set flags ADDGE r2, r2, r3       ; if (r0 >= r1) then r2 := r2 + r3; ADDLT r2, r2, r4       ; else r2 := r2 + r4; A 32-bit barrel shifter can be used without performance penalty with most arithmetic instructions and address calculations: ADD r2, r3, r3, lsl #2 ; r2 := r3 + (r3 << 2) ; → r2 := r3 + r3 * 4 ; → r2 := r3 * 5 =Computer Chess= The ARM2 processor was embedded inside the TASC ChessMachine plugged in as ISA card inside an IBM PC, running Gideon and The King, and was further used in various dedicated chess computers by Hegener & Glaser such as the Mephisto RISC.

=See also=
 * Acorn Archimedes
 * ARM6

=Manuals=
 * ARM® and Thumb®-2 Instruction Set Quick Reference Card (pdf)
 * ARM Assembly Language Programming by Pete Cockerell

=Postings=
 * Some facts about the Acorn RISC Machine by Roger Wilson, comp.arch, November 02, 1988
 * StrongARM speed of Streater program (was Re: M-Chess Pro 6.0 program description) by Stephen B. Streater, rgcc, October 21, 1996 » reply to Ed Schröder on ARM2 vs. StrongARM

=External Links=
 * Acorn RISC Machine: ARM2 from Wikipedia
 * Amber (processor core) from Wikipedia
 * ARM2 - Microarchitectures - Acorn - WikiChip
 * ARM3 - Microarchitectures - Acorn - WikiChip
 * ARMwiki
 * ARM Assembler
 * Instruction set quick finder
 * ARM from Schachcomputer.info Wiki
 * RISC OS from Wikipedia
 * ARM Hardware Overview
 * ARM Information Center
 * Race to Embedded World Domination by Paul DeMone, Real World Tech, November 9, 2000

=References= Up one Level