MC68HC05V12 Datasheet, PDF (52/246 Pages) Freescale Semiconductor, Inc – HCMOS Microcontreller Unit

Freescale Semiconductor, Inc.
Central Processor Unit (CPU)
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.
Bit
Bit
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Read:
Write:
Reset: 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
Figure 3-4. Stack Pointer (SP)
3.3.4 Program Counter
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.
Bit
Bit
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Read:
00
5
Write:
Reset: 0 0
Loaded with vectors from $3FF3 and $3FFF
Figure 3-5. Program Counter (PC)
Technical Data
Central Processor Unit (CPU)
For More Information On This Product,
Go to: www.freescale.com
MC68HC05V12 — Rev. 2.0