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LCD-IV
• Program Counter (PC)
The program counter is used for addressing of ROM. The
program counter consists of the bank part, the page part, and
the address part as shown in Figure 2.
Bank
Page
Address
o
Page
P
L
1 Page
lJ
30 Page
31 Page
lL
L
3F Address
3E Address
OF Address
1F Address
3F Address
3E Address
Bank ' - - - - - ~:~---~
L -_ _ _ _
:a~~ress
,art
I
L . .
---(Page Partl----'
Note: The parenthesized contents are expressions of the
Page,combining the bank part with the page part.
Figure 2 Configuration of Program Counter
The bank part is a I-bit register and the page part is as-bit
register.
Table 1 Program Counter Address Part Sequence
Once a certain value is loaded into the bank part or the page
part, the content is unchanged until other value is loaded by a
program.
The settable value is "0" (the Bank 0) or "I" (the Bank I)
for the bank part, and 0 to 31 for the page part.
The address part is a 6-bit polynomial counter and counts up
for each instruction cycle time. The sequence in the decimal and
hexa-decimal system is shown in Table 1. This sequence is cir-
culating and has neither the starting nor ending point. It doesn't
generate an overflow carry. Consequently, the program on a
same page is executed in order unless the value of the bank part
or the page part is changed.
187
Decimal
63
62
61
59
55
47
30
60
57
51
39
14
29
58
53
43
22
44
24
48
33
2
Hexa-
Decimal
decimal
3F
5
3E
11
3D
23
38
46
37
28
2F
56
1E
49
3C
35
39
6
33
13
27
27
OE
54
10
45
3A
26
35
52
28
41
16
18
2C
36
18
8
30
17
21
34
02
4
Hexa-
Decimal
Hexa-
decimal
decimal
05
9
09
OB
19
13
17
38
26
2E
12
OC
1C
25
19
38
50
32
31
37
25
23
10
OA
06
21
15
00
42
2A
1B
20
14
36
40
28
20
16
10
1A
32
20
34
0
00
29
1
01
12
3
03
24
7
07
08
15
OF
11
31
1F
22
04
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