MC68HC812A4 Datasheet, PDF (60/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Central Processor Unit (CPU12)
3.3 Programming Model
CPU12 registers are an integral part of the CPU and are not addressed
as if they were memory locations. See Figure 3-1.
7
A
07
B
0 8-BIT ACCUMULATORS A AND B
15
D
0 16-BIT DOUBLE ACCUMULATOR D (A : B)
15
X
0 INDEX REGISTER X
15
Y
0 INDEX REGISTER Y
15
SP
0 STACK POINTER
15
PC
0 PROGRAM COUNTER
S X H I N Z V C CONDITION CODE REGISTER
CARRY
OVERFLOW
ZERO
NEGATIVE
IRQ INTERRUPT MASK (DISABLE)
HALF-CARRY FOR BCD ARITHMETIC
XIRQ INTERRUPT MASK (DISABLE)
STOP DISABLE (IGNORE STOP OPCODES)
Figure 3-1. Programming Model
3.4 CPU Registers
This section describes the CPU registers.
MC68HC812A4 — Rev. 3.0
60
Central Processor Unit (CPU12)
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