> That's... not the way hardware works. Those transistors are still there, it's not like you can make them go away by switching "modes". First, even in T32 mod

> That's... not the way hardware works. Those transistors are still there, it's not like you can make them go away by switching "modes". First, even in T32 mode, there are only two instruction lengths, 2 and 4 bytes. Requires much less transistors than modern Intel and AMD CPUs which supports single cycle decoding of instruction lengths from 1 to 15 bytes. Second, due to prefix bytes, the bits which control the x64 instruction length a spread all throughout the instruction, and they interact with each other. There are instructions where every single byte modifies the length. Decoding variable length T32 is easy, there are only a few bits in the first byte that select between 16 and 32bit. Third, T32 support is technically optional. Apple has required all apps to be recompiled in A64 mode for years, I'm not even sure if their latest CPUs still support switching to T32 mode. Forth, mode switching does use less transistors than a design that has to chose on a per-instruction basis. It takes a lot of extra transistors to dynamically detect the instruction type, which have to be replicated 4 or 8 times are unnecessary. All you need is a single bit register to store the current state and a special instruction to switch between modes.