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MC9S08QD4_08 Datasheet, PDF (75/202 Pages) Freescale Semiconductor, Inc – Microcontrollers | |||
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Chapter 7
Central Processor Unit (S08CPUV2)
7.1 Introduction
This section provides summary information about the registers, addressing modes, and instruction set of
the CPU of the HCS08 Family. For a more detailed discussion, refer to the HCS08 Family Reference
Manual, volume 1, Freescale Semiconductor document order number HCS08RMV1/D.
The HCS08 CPU is fully source- and object-code-compatible with the M68HC08 CPU. Several
instructions and enhanced addressing modes were added to improve C compiler efficiency and to support
a new background debug system which replaces the monitor mode of earlier M68HC08 microcontrollers
(MCU).
7.1.1 Features
Features of the HCS08 CPU include:
⢠Object code fully upward-compatible with M68HC05 and M68HC08 Families
⢠All registers and memory are mapped to a single 64-Kbyte address space
⢠16-bit stack pointer (any size stack anywhere in 64-Kbyte address space)
⢠16-bit index register (H:X) with powerful indexed addressing modes
⢠8-bit accumulator (A)
⢠Many instructions treat X as a second general-purpose 8-bit register
⢠Seven addressing modes:
â Inherent â Operands in internal registers
â Relative â 8-bit signed offset to branch destination
â Immediate â Operand in next object code byte(s)
â Direct â Operand in memory at 0x0000â0x00FF
â Extended â Operand anywhere in 64-Kbyte address space
â Indexed relative to H:X â Five submodes including auto increment
â Indexed relative to SP â Improves C efficiency dramatically
⢠Memory-to-memory data move instructions with four address mode combinations
⢠Overflow, half-carry, negative, zero, and carry condition codes support conditional branching on
the results of signed, unsigned, and binary-coded decimal (BCD) operations
⢠Efficient bit manipulation instructions
⢠Fast 8-bit by 8-bit multiply and 16-bit by 8-bit divide instructions
⢠STOP and WAIT instructions to invoke low-power operating modes
MC9S08QD4 Series MCU Data Sheet, Rev. 5
Freescale Semiconductor
75
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