Freescale Semiconductor, Inc.
November 5, 1998
GENERAL RELEASE SPECIFICATION
SECTION 3
CENTRAL PROCESSING UNIT
The MC68HC05JB3 has an 8k-bytes memory map. The stack has only 64 bytes.
Therefore, the stack pointer has been reduced to only 6 bits and will only
decrement down to $00C0 and then wrap-around to $00FF. All other instructions
and registers behave as described in this chapter.
3.1
REGISTERS
The MCU contains five registers which are hard-wired within the CPU and are not
part of the memory map. These five registers are shown in Figure 3-1 and are
described in the following paragraphs.
7
6
5
4
3
2
1
0
ACCUMULATOR
INDEX REGISTER
A
X
15
0
14
0
13
0
12
0
11
0
10
0
9
0
8
0
1
1
STACK POINTER
SP
PC
CC
PROGRAM COUNTER
CONDITION CODE REGISTER
1
1
1
H
I
N
Z
C
HALF-CARRY BIT (FROM BIT 3)
INTERRUPT MASK
NEGATIVE BIT
ZERO BIT
CARRY BIT
Figure 3-1. MC68HC05 Programming Model
MC68HC05JB3
REV 1
CENTRAL PROCESSING UNIT
MOTOROLA
3-1
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