
Overview
1-12
ColdFire2/2M User’s Manual
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MOTOROLA
1.4.1.1 DATA REGISTERS (D0 – D7) .
(1 bit), byte (8 bits), word (16 bits), and long word (32 bits) operations and may also be used
as index registers.
Registers D0–D7 are used as data registers for bit
1.4.1.2 ADDRESS REGISTERS (A0 – A6) .
stack pointers, index registers, or base address registers and may be used for word and long
word operations.
These registers can be used as software
1.4.1.3 STACK POINTER (A7,SP) .
pointer (A7) used during stacking for subroutine calls, returns, and exception handling. The
initial value of A7 is loaded from the reset exception vector, address $0. The same register
is used for user mode and supervisor mode, and may be used for word and long word
operations.
ColdFire2/2M supports a single hardware stack
A subroutine call saves the PC on the stack, and the return restores the PC from the stack.
Both the PC and the Status Register (SR) are saved on the stack during the processing of
exceptions and interrupts. The return from exception instruction restores the SR and PC
values from the stack.
1.4.1.4 PROGRAM COUNTER (PC).
executing instruction. During instruction execution and exception processing, the processor
automatically increments the contents of the PC or places a new value in the PC, as
appropriate. For some addressing modes, the PC can be used as a pointer for PC-relative
operand addressing.
The PC contains the address of the currently
1.4.1.5 CONDITION CODE REGISTER (CCR).
processor Status Register (SR), as shown in
Figure 1-6
. Bits 4–0 represent indicator flags
The CCR is the least significant byte of the
31
16
15
8
7
0
Data Register 0 (D0)
Data Register 1 (D1)
Data Register 2 (D2)
Data Register 3 (D3)
Data Register 4 (D4)
Data Register 5 (D5)
Data Register 6 (D6)
Data Register 7 (D7)
Address Register 0 (A0)
Address Register 1 (A1)
Address Register 2 (A2)
Address Register 3 (A3)
Address Register 4 (A4)
Address Register 5 (A5)
Address Register 6 (A6)
Stack Pointer (SP,A7)
Program Counter (PC)
Condition Code Register (CCR)
Figure 1-5. Integer Unit User Programming Model
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