6 ms·
> Many (most? citation needed) current, mainstream CPUs use the same bit width for all three (address, data, register). This is quite wrong, for most x86_64 pr
by zeusk 3y ago
> Many (most? citation needed) current, mainstream CPUs use the same bit width for all three (address, data, register).
This is quite wrong, for most x86_64 processors:
Address bus is 42-48 bits
Data bus is 32-128 bits
Registers are 64 bits but usable as 32/16/8 bits
Even on most ARM processors, neither the address bus nor the data bus are same width as either or the register width.
- daggersandscars 3y agoAwesome! Thank you for posting this. I'd edit my response to include this, but it's too late.
- fanf2 3y agoDon’t forget the SIMD registers which can be 128/256/512 wide (neon/avx2/avx512) It’s very difficult to give just a single number for data bus width. Do you add all the DRAM channels? DDR5 has 2 x 32 bit channels where DDR4 has a 64 bit channel. What does bus width mean for PCIe, which uses very fast differential serial lines? Really, it hasn’t been a useful way to describe system performance since the 1990s.