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2-2
(A6-AO) and the stack pointer (USP in user space) may be used as software
stack pointers and base address registers. In addition, the address registers
may be used for word and long-word operations. All 16 registers may be
used as index registers.
The supervisor's programming model includes supplementary registers, in-
cluding the supervisor stack pointer (SSP) and the status register (SR) as
shown in Figure 2-2. The SR contains the interrupt mask (eight levels avail-
31
16 15
8 7
0
DO
01
02
03
DATA REGISTERS
04
05
06
07
31
16 15
0
AO
Al
A2
A3
ADDRESS REGISTERS
A4
A5
A6
31
0
A7IUSP) A7 USER STACK POINTER
31
0
PC
PROGRAM COUNTER
USER MODE
7
0
I
I
CCR
CONDITION CODE REGISTER
31
16 15
0
A7'ISSP) SUPERVISOR STACK POINTER
15
8 7
0
SUPERVISOR
I
I
CCR
I
SR
STATUS REGISTER
MODE
Figure 2-1. M68000 Programming Model
MC68302 USER'S MANUAL
MOTOROLA
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