More ARM1 processor reverse engineering: the priority encoder

In a previous post, Ken Shirriff reverse engineered the silicon in the ARM1 processor, this time he reverse-engineer the priority encoder in the ARM1 processor: In this article, I reverse-engineer the priority encoder in the ARM1 processor. By examining the chip layout provided by the Visual ARM1 project, I have determined how this circuit works […]

Counting bits in hardware: Reverse engineering the silicon in the ARM1 processor

Ken Shirriff writes: 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 […]

Reverse engineering the ARM1, ancestor of the iPhone’s processor

Another great article from Ken Shirriff, this time on reverse engineering the ARM1: Almost every smartphone uses a processor based on the ARM1 chip created in 1985. The Visual ARM1 simulator shows what happens inside the ARM1 chip as it runs; the result (below) is fascinating but mysterious.[1] In this article, I reverse engineer key […]