The main component of the Amiga 500 is the CPU. It is a motorola processor 68000.
The speed is 7 Mhz (!)
The CPU is 16/32 bits (internal registers are 32 bits). There are 16 registers:
D0 to D8 : Data register
A0 to A8 : Adress register
SP (Stack pointer) is equivalent to A7.
There are 56 instructions. One instruction size can go from 16 bits to longer size.
Instruction « RTS » (Return from subroutine) is 0x4E75.
Instruction « NOP » (No operation) is 0x4E71.
Full list of instructions HERE.
The format for writing instruction is SOURCE,DEST. For example « Move #4,d0 » will copy value 4 (source) to register D0 (destination). Some processor (like intel) used the inverse notation (Instruction Dest, source).
The CPU have 7 levels of « interuptions », we’ll see that later.