MC68HC05P9ACDW FREESCALE [Freescale Semiconductor, Inc], MC68HC05P9ACDW Datasheet - Page 33

• Manufacturer Part Number: MC68HC05P9ACDW
• Description: HCMOS Microcontroller Unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

11-hc05cpu
MOTOROLA
H — Half-Carry Flag
I — Interrupt Mask
N — Negative Flag
Z — Zero Flag
C — Carry/Borrow Flag
The CPU sets the half-carry flag when a carry occurs between bits 3
and 4 of the accumulator during an ADD or ADC operation. The
half-carry flag is required for binary-coded decimal (BCD) arithmetic
operations.
Setting the interrupt mask disables interrupts. If an interrupt request
occurs while the interrupt mask is logic zero, the CPU saves the CPU
registers on the stack, sets the interrupt mask, and then fetches the
interrupt vector. If an interrupt request occurs while the interrupt mask
is set, the interrupt request is latched. Normally, the CPU processes
the latched interrupt as soon as the interrupt mask is cleared again.
A return from interrupt (RTI) instruction pulls the CPU registers from
the stack, restoring the interrupt mask to its cleared state. After any
reset, the interrupt mask is set and can be cleared only by a software
instruction.
The CPU sets the negative flag when an arithmetic operation, logical
operation, or data manipulation produces a negative result.
The CPU sets the zero flag when an arithmetic operation, logical
operation, or data manipulation produces a result of $00.
The CPU sets the carry/borrow flag when an addition operation
produces a carry out of bit 7 of the accumulator or when a subtraction
operation requires a borrow. Some logical operations and data
manipulation instructions also clear or set the carry/borrow flag.
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CPU
CPU Registers
CPU
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