STM8 Core

• memory and register map
• pipeline
• addressing modes
• instruction set

8 bit architecture

• 6 internal registers
• 80 instructions
• 20 addressing modes

Registers

• (A) Accumulator
• (X) X index & (Y) Y index
• (SP) Stack Pointer
• (PC) Program Counter
• (CC) Code Condition (Status register?)

STM8 core context saving

STM8 during interrupt is saving whole context (registers) to stack (pushing to the stack) using 9 clock cycles for that, then poping afterwards. This allows for good recovery after interrupt, However this slows down the procedure compared to simply changing one register (program counter).

Memory interface

• Page 0 - 1 byte addressing
• Section 0 - 2 byte addressing