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 reverse engineering the silicon in the ARM1 processor 
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Joined: Wed Jan 16, 2013 2:33 am
Posts: 165
Reverse engineering the silicon in the ARM1 processor

How can you count bits in hardware? In this article, I reverse-engineer the circuit used by the ARM1 processor to count the number of set bits in a 16-bit field, showing how individual transistors form multiplexers, which are combined into adders, and finally form the bit counter. The ARM1 is the ancestor of the processor in most cell phones, so you may have a descendent of this circuit in your pocket.

ARM is now the world's most popular instruction set but it has humble beginnings. The original ARM1 processor was designed in 1985 by a UK company called Acorn Computer for the BBC Micro home/educational computer. A few years later Apple needed a low-power, high-performance processor for its ill-fated Newton handheld system and chose ARM.[1] In 1990, Acorn Computers, Apple, and chip manufacturer VLSI Technology formed the company Advanced RISC Machines to continue ARM development. ARM became very popular for low power applications (such as phones) and now more than 50 billion ARM processors have been manufactured. ... verse.html

Wed Jan 13, 2016 5:52 pm

Joined: Wed Jan 09, 2013 6:54 pm
Posts: 1644
Ken Shirriff and Dave Mugridge are both producing a series of blog posts - all worth reading, on past experience. Let's use this thread to discuss any and all points arising from both. Or any other observations on ARM1, whether or not derived from visual6502's visualARM!

Ken's previous post: ... or-of.html

Dave's index post: ... t-arm.html

(Declaration of interest: I had a part to play in visualARM)

Wed Jan 13, 2016 6:06 pm
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