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When writing to a register, say, like mov ax, 1, it overwrites the value it may have had earlier.
Now what I wonder is that how big figures/strings can I feed into a register, and that can another application overwrite my app’s register values? I mean, are the registers shared among processes or do they receive their own sandboxed/virtual registers?
I am interesting in Intel x86(-64) Core CPUs and Windows.
Only one thread is scheduled at a time on a single core. The core is what has the registers.
When a new thread is scheduled, the registers are first saved, and the previously-saved registers of the thread are restored. This includes the Program Counter register, which points to the next instruction to execute.
Registers (from memory):
AX, BX, CX, DX are 16 bits, broken into bytes (AH, AL, BH, BL)
SI, DI, SP and BP are also 16 bits
EAX, EBX, ECX etc. are 32 bits
I’m not sure what they’re called on a 64-bit system. I think I saw RAX, but I’m not sure.
There are also special-purpose registers, floating-point registers, etc.