UPSD3254 STMICROELECTRONICS [STMicroelectronics], UPSD3254 Datasheet - Page 21

• Manufacturer Part Number: UPSD3254
• Description: Flash Programmable System Devices with 8032 Microcontroller Core
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

SFR
The SFRs can only be addressed directly in the
address range from 80h to FFh. Table 15, page 33
gives an overview of the Special Function Regis-
ters. Sixteen address in the SFRs space are both-
byte and bit-addressable. The bit-addressable
SFRs are those whose address ends in 0h and 8h.
The bit addresses in this area are 80h to FFh.
Table 3. RAM Address
Byte Address
(in Hexadecimal)
FFh
2Eh
2Dh
2Ch
2Bh
2Ah
30h
2Fh
29h
28h
27h
26h
25h
24h
23h
22h
21h
20h
1Fh
18h
17h
10h
0Fh
08h
07h
00h
msb
7F
6F
5F
4F
3F
2F
1F
0F
77
67
57
47
37
27
17
07
7E
6E
5E
4E
3E
2E
1E
0E
76
66
56
46
36
26
16
06
7D
6D
5D
4D
3D
2D
1D
0D
75
65
55
45
35
25
15
05
Bit Address (Hex)
Register Bank 3
Register Bank 2
Register Bank 1
Register Bank 0
7C
6C
5C
4C
3C
2C
1C
0C
74
64
54
44
34
24
14
04
7B
73
6B
63
5B
53
4B
43
3B
33
2B
23
1B
13
0B
03
7A
6A
5A
4A
3A
2A
1A
0A
72
62
52
42
32
22
12
02
Byte Address
79
71
69
61
59
51
49
41
39
31
29
21
19
09
01
11
(in Decimal)
UPSD3254A, UPSD3254BV, UPSD3253B, UPSD3253BV
lsb
78
70
68
60
58
50
48
40
38
30
28
20
18
10
08
00
255
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
24
23
16
15
8
7
0
Addressing Modes
The addressing modes in uPSD325X devices in-
struction set are as follows
(1) Direct addressing. In a direct addressing the
operand is specified by an 8-bit address field in the
instruction. Only internal Data RAM and SFRs
(80~FFH RAM) can be directly addressed.
Example:
Figure 11. Direct Addressing
(2) Indirect addressing. In indirect addressing
the instruction specifies a register which contains
the address of the operand. Both internal and ex-
ternal RAM can be indirectly addressed. The ad-
dress register for 8-bit addresses can be R0 or R1
of the selected register bank, or the Stack Pointer.
The address register for 16-bit addresses can only
be the 16-bit “data pointer” register, DPTR.
Example:
Figure 12. Indirect Addressing
Direct addressing
Indirect addressing
Register addressing
Register-specific addressing
Immediate constants addressing
Indexed addressing
mov A, 3EH ; A <----- RAM[3E]
mov @R1, #40 H ;[R1] <-----40H
3Eh
55h
R1
Program Memory
Program Memory
40h
04
55
A
AI06641
AI06642
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