MC68HC705J1ACPE Datasheet, PDF (46/162 Pages) Freescale Semiconductor, Inc – Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.
Central Processor Unit (CPU)
3.2 Introduction
The central processor unit (CPU) consists of a CPU control unit, an
arithmetic/logic unit (ALU), and five CPU registers. The CPU control unit
fetches and decodes instructions. The ALU executes the instructions.
The CPU registers contain data, addresses, and status bits that reflect
the results of CPU operations. See Figure 3-1.
Features include:
• 2.1-MHz bus frequency
• 8-bit accumulator
• 8-bit index register
• 11-bit program counter
• 6-bit stack pointer
• Condition code register (CCR) with five status flags
• 62 instructions
• Eight addressing modes
• Power-saving stop, wait, halt, and data-retention modes
3.3 CPU Control Unit
The CPU control unit fetches and decodes instructions during program
operation. The control unit selects the memory locations to read and
write and coordinates the timing of all CPU operations.
3.4 Arithmetic/Logic Unit
The arithmetic/logic unit (ALU) performs the arithmetic, logic, and
manipulation operations decoded from the instruction set by the CPU
control unit. The ALU produces the results called for by the program and
sets or clears status and control bits in the condition code register
(CCR).
Technical Data
MC68HC705J1A — Rev. 4.0
Central Processor Unit (CPU)
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