Table of Contents
Advertisement
CPU
15
PS
HARDWARE CONFIGURATION
Internal Registers in CPU
The MB89140 series of microcontrollers have dedicated registers in the
CPU and general-purpose registers in memory.
Program counter (PC)
Accumulator (A)
Temporary accumulator (T)
Stack pointer (SP)
Processor status (PS)
Index register (IX)
Extra pointer (EP)
16 bits
P C
A
T
IX
EP
SP
PS
The 16 bits of the processor status (PS) can be divided into 8 upper bits for a
register bank pointer (RP) and 8 lower bits for a condition code register
(CCR). (See Figure 2.4.)
14
13
12
11
10
RP
Vacant Vacant Vacant
RP
Fig. 2.4 Structure of Processor Status
2-6
16-bit long register indicating location
where instructions stored
16-bit long register where results of opera-
tions stored temporarily; the lower byte is
used to execute 8-bit data processing
instructions.
16-bit long register; the operations are per-
formed between this register and the accu-
mulator. The lower one byte is used to
execute 8-bit data processing instructions
16-bit long register indicating stack area
16-bit long register where register pointers
and condition codes stored
16-bit long register for index modification
16-bit long register for memory addressing
Program counter
Accumulator
Temporary accumulator
Index register
Extra pointer
Stack pointer
Processor status
9
8
7
6
5
4
IL1, 0
H
I
CCR
3
2
1
0
N
Z
V
C
Advertisement
Table of Contents
