The Silent Invasion

Acorn RISC Machine

or

Advanced RISC Machine?

You own an ARM machine!(or several dozen)

• Over 75% of the embedded device market is powered by ARM

• ARM is small

• Requires low power

• Efficient performance

• CHEAP TO MANUFACTURE

• Jazelle technology

• Thumb 2

• Enhanced DSP

• Up to 200MHZ

• As small as 90nm

ARM926EJ-S

Odd features of the ARM Model

• Every instruction has a condition code

This means that you don’t necessarily have to branch around.

• Shifting and rotating can be embedded in other arithmetic instructions.

•An actually useful interrupt system

Registers

• ARM is load-store

• Has 37 registers

• You can only see 16 in main software mode

• You can only really use the first 13

• R13, R14, and R15 are the stack pointer, link pointer, and the PC respectively

Instruction formatVirginia Lo:Virginia Lo:

NOBODY EXPECTS YOU TO MEMORIZE IT!

Instructions

• ADD – Standard Addition• ADC – Add with carry• QADD – Saturated add• QDADD – Double saturated add

• B – Branch… if you don’t know what this does, good luck on the final

• BL – Branch and link

An odd instruction

• BX – Branch and exchange

• BXL – Branch, exchange, and link