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CHAPTER 7 SYSTEM REGISTER (SYSREG)
60
7.6.2 Functions of the General Register Pointer
The general register pointer is used to specify the location of the general register in data memory. For a more
detailed explanation, refer to
CHAPTER 8 GENERAL REGISTER (GR)
.
The general register consists of sixteen nibbles in any single row of data memory. As shown in Figure 7-15, the
general register pointer is used to indicate which row address is being used as the general register.
Since the general register pointer effectively consists of three bits, the data memory row addresses in which the
general register can be placed are address locations 0H to 7H of BANK0. In other words, any row in data memory
can be specified as the general register.
With the general register allocated in data memory, data can be transferred to and from, and arithmetic/logical
operations can be performed on the general register and data memory.
Note that addresses 40H to 6EH are uninstalled memory locations and should therefore not be specified as
locations for the general register.
For example, when instructions such as
ADD r,m and LD r,m
are executed, instruction operand r can specify an address in the general register and m specifies an address in data
memory. In this way, operations like addition and data transfer can be performed on and between data memory
and the general register.
Figure 7-15. General Register Configuration
Notes
1.
These bits should not be specified in the case of the
µ
PD17120 and 17121.
2.
This bit is allocated to BCD flag.
b
1
0
1
0
1
0
1
0
1
b
2
0
0
1
1
0
0
1
1
b
3
0
0
0
0
1
1
1
1
b
0
b
1
b
2
b
3
b
0
Fixed to 0
Fixed to 0
Fixed to 0
Fixed to 0
Note
2
RPH
RPL
Note 1
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
8
9
A B C D E
F
BP
General register (16 nibbles)
System register
BANK0
General register pointer
(RP)
Example :
General
register
with
RPH=0000B
RPL=010
×
B
Area in which
general register
can be specified
Column address
Содержание mPD17120 Subseries
Страница 15: ... x MEMO ...
Страница 23: ... MEMO 8 ...
Страница 45: ... MEMO 30 ...
Страница 49: ... MEMO 34 ...
Страница 55: ... MEMO 40 ...
Страница 93: ... MEMO 78 ...
Страница 99: ... MEMO 84 ...
Страница 102: ...CHAPTER 11 ARITHMETIC AND LOGIC UNIT 87 MEMO ...
Страница 119: ... MEMO 104 ...
Страница 175: ... MEMO 160 ...
Страница 199: ... MEMO 184 ...
Страница 265: ... MEMO 250 ...
Страница 281: ...266 MEMO ...
Страница 285: ... MEMO 270 ...
Страница 289: ... MEMO 274 ...