MC68HC705V12CFN MOTOROLA [Motorola, Inc], MC68HC705V12CFN Datasheet - Page 52

• Manufacturer Part Number: MC68HC705V12CFN
• Description: The Motorola microcontroller
• Manufacturer: MOTOROLA [Motorola, Inc]

Central Processor Unit (CPU)
3.3.4 Program Counter
Advance Information
52
Reset:
Read:
Write:
Read:
Write:
Reset
Bit
15
Bit
15
0
0
0
14
14
0
0
0
13
13
0
The 10 most significant bits of the stack pointer are permanently fixed at
000000011, so the stack pointer produces addresses from $00C0 to
$00FF. If subroutines and interrupts use more than 64 stack locations,
the stack pointer wraps around to address $00FF and begins writing
over the previously stored data. A subroutine uses two stack locations.
An interrupt uses five locations.
The program counter (PC) is a 16-bit register that contains the address
of the next instruction or operand to be fetched. The two most significant
bits of the program counter are ignored internally and appear as 00.
Normally, the address in the program counter automatically 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.
12
12
0
Figure 3-5. Program Counter (PC)
11
11
0
Figure 3-4. Stack Pointer (SP)
Central Processor Unit (CPU)
10
10
0
Loaded with vectors from $3FF3 and $3FFF
9
0
9
8
0
8
7
1
7
6
1
6
5
1
5
4
1
4
MC68HC705V12
3
1
3
5
2
1
2
MOTOROLA
—
1
1
1
Rev. 3.0
Bit
Bit
0
1
0