Zilog Z8F0130 - Manual (Page 17)

eZ8
™
CPU Core
User Manual
UM012820-0810 Architectural Overview
2
Fetch Unit
The Fetch Unit controls the memory interface. Its primary function is to
fetch Op Codes and operands from memory. The Fetch Unit also fetches
interrupt vectors or reads and writes memory in the Program or Data
Memory.
The Fetch Unit performs a partial decoding of the Op Code to determine
the number of bytes to fetch for the operation. The Fetch Unit operation
sequence is as follows:
1. Fetch the Op Code.
2. Determine the operand size (number of bytes).
3. Fetch the operands.
Figure 1. eZ8 CPU Block Diagram
Fetch Unit
Instruction
State Machine
CPU Control
Registers
Program
Counter
Arithmetic Logic Unit