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CHAPTER 5 DATA MEMORY (RAM)
33
5.1.4 Port Registers
A port register consists of five nibbles allocated at addresses 6FH to 73H in Bank0 of the data memory. As shown
in Figure 5-5, the two high-order bits of address 6FH are always set to 0.
Figure 5-5 shows the configuration of the port registers.
Figure 5-5. Port Register Configuration
Port Register
Address
6FH
70H
71H
72H
73H
P0E
P0A
P0B
P0C
P0D
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
E
E
A
A
A
A
B
B
B
B
C
C
C
C
D
D
D
D
1
0
3
2
1
0
3
2
1
0
3
2
1
0
3
2
1
0
5.1.5 General Data Memory
General data memory is all the data memory not used by the port and system registers (SYSREG). In other words,
general data memory consists of 64 nibbles (
µ
PD17120 and 17121) or 111 nibbles (
µ
PD17132, 17133, 17P132, and
17P133).
5.1.6 Uninstalled Data Memory
There is no hardware installed at addresses 40H to 6EH of the
µ
PD17120 and 17121. Any attempt to read this
area will yield unpredictable results. Writing data to this area is invalid and should therefore not be attempted.
Figure 5-4. General Register (GR) Configuration
Symbol
0
0
BANK0
Area specifiable as general register
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
BANK0
Port register
Row address
Column address
SYSREG
General register
Pointed to by general register
pointer (RP) in system register.
Note that row addresses 4 to 6
in the case of the PD17120
and 17121 are uninstalled mem-
ory locations. The register
pointer (RP) should therefore
not specify a row address in this
area.
µ
Summary of Contents for mPD17120 Subseries
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