HMCS46C,HMCS46CL----------------------------------
__________________
__
• 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
L....---....;.0
p----,age
I}
I
~
..... L
30
Page
31
Page
Address
3F Address
3E
Address
Bank
'-----
~:~
___
-J
'-----~:res.
{art
1....
---(PagePartl~
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
a S·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
"1"
(the Bank 1)
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.
90
Decimal
63
62
61
69
66
47
30
60
67
61
39
14
29
68
63
43
22
44
24
48
33
2
Hexa·
Decimal
decimal
3F 6
3E
11
3D
23
3B
46
37 28
2F
66
1E
49
3C 36
39 6
33
13
27 27
OE
64
10
46
3A
26
36
62
28
41
16 18
2C
36
18
8
30 17
21
34
02 4
Hexa·
Decimal
Hexa·
decimal
decimal
06
9
09
OB
19
13
17 38
26
2E
12
OC
1C
26
19
38
60
32
31
37
26
23
10
OA
06
21
16
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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