MC68HC05P1ADW FREESCALE [Freescale Semiconductor, Inc], MC68HC05P1ADW Datasheet - Page 34

• Manufacturer Part Number: MC68HC05P1ADW
• Description: General Release Specification
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

CPU Core
3.3.4 Program Counter
3.3.5 Condition Code Register
General Release Specification
and loses the previously stored information. A subroutine call occupies
two locations on the stack; an interrupt uses five locations.
The program counter (PC) is a 13-bit register that contains the address
of the next byte to be fetched. Because addresses are often 16-bit
values, the program counter may be thought of as having three
additional upper bits that are always zeros.
Normally, the address in the program counter increments to the next
sequential memory location every time an instruction or operand is
fetched. Jump, branch, and interrupt operations load the program
counter with an address other than that of the next sequential location.
The condition code register (CCR) is a 5-bit register in which the H, N,
Z, and C bits are used to indicate the results of the instruction just
executed, and the I bit is used to enable or disable interrupts. These bits
can be individually tested by a program, and specific actions can be
taken as a result of their state. Consider the condition code register as
having three additional upper bits that are always ones.
H — Half Carry
15
0
This bit is set during ADD and ADC operations to indicate that a carry
occurred between bits 3 and 4.
Freescale Semiconductor, Inc.
For More Information On This Product,
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Go to: www.freescale.com
12
12
0
CPU Core
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7
1
0
1
0
1
0
H
4
7
1
I
3
PC
1
2
N
50
MC68HC05P1A
Z
1
C
SP
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Rev. 3.0
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