Semiconductor Group
1-4
1998-04-01
Fundamental Structure
C500 Family
shows the configuration of the three basic internal RAM areas. The lower data RAM is
located in the address range 00H - 7FH and can be addressed directly (e.g. MOV A,direct) or
indirectly (e.g. MOV A,@R0 with address in R0). A bit-addressable area of 128 free programmable,
direct addressable bits is located at byte addresses 20H - 2FH of the lower data RAM. Bit 0 of the
internal data byte at 20H has the bit address 00H while bit 7 of the internal data byte at 2FH has the
bit address 7FH. The lower 32 locations of the internal lower data RAM are assigned to four banks
with eight general purpose registers (GPRs) each. Only one of these banks can be enabled at a
time to be used as general purpose registers.
Figure 1-2
Internal Data Memory Organization
MCD02767
FF FE FD FC FB FA F9 F8
FF H
F8 H
H
F0
F0
F1
F2
F3
F4
F5
F6
F7
H
E8
E8
E9
EA
EB
EC
ED
EE
EF
H
E0
E0
E1
E2
E3
E4
E5
E6
E7
H
D8
D8
D9
DA
DB
DC
DD
DE
DF
H
D0
D0
D1
D2
D3
D4
D5
D6
D7
H
C8
C8
C9
CA
CB
CC
CD
CE
CF
H
C0
C0
C1
C2
C3
C4
C5
C6
C7
H
B8
B8
B9
BA
BB
BC
BD
BE
BF
H
B0
B0
B1
B2
B3
B4
B5
B6
B7
H
A8
A9
A8
AA
AC
AB
AD
AE
AF
H
A0
A0
A1
A2
A3
A4
A5
A6
A7
H
98
99
98
9A
9C
9B
9D
9E
9F
H
90
90
91
92
93
94
95
96
97
H
88
89
88
8A
8C
8B
8D
8E
8F
H
80
80
81
82
83
84
85
86
87
Internal SFR Area
(direct addressable)
Byte
128
7F H
7F 7E 7D 7C 3B 7A 79 78
H
30
2F H
70
71
72
73
74
75
76
77
2E H
68
69
6A
6B
6C
6D
6E
6F
2D H
60
61
62
63
64
65
66
67
2C H
58
59
5A
5B
5C
5D
5E
5F
2B H
50
51
52
53
54
55
56
57
2A H
48
49
4A
4B
4C
4D
4E
4F
29 H
40
41
42
43
44
45
46
47
28 H
38
39
3A
3B
3C
3D
3E
3F
27 H
30
31
32
33
34
35
36
37
26 H
28
29
2A
2B
2C
2D
2E
2F
25 H
20
21
22
23
24
25
26
27
24 H
18
19
1A
1B
1C
1D
1E
1F
23 H
10
11
12
13
14
15
16
17
22 H
08
09
0A
0B
0C
0D
0E
0F
21 H
00
01
02
03
04
05
06
07
H
20
R0
H
00
R1
H
01
R2
H
02
R3
H
03
R4
H
04
R5
H
05
R6
H
06
R7
H
07
08 H
1F H
18
17
H
H
10
0F
H
H
RAM Area
~
~
~
~
Registerbank 0
Registerbank 2
Registerbank 3
Registerbank 1
H
FF
H
7F
H
80
00 H
128 Byte
(indirect & direct
Lower
addressable)
Internal Data
RAM
RAM
Internal Data
addressable)
Upper
(indirect
128 Byte
1)
1) This internal RAM area is optional. Some low-end C500 family microcontrollers don't
provide this internal RAM area.
16 Bytes with 128 bitaddressable Bits