--------------------------------------------------------HMCS46C,HMCS46CL
The I-bit latches are attached
to
these terminals. Each ter-
minal
is
addressed by the Y register. The
Do
to
D3
terminals are
also addressed directly by the operand
of
input/output instruc-
tion. Refer
to
INPUT/OUTPUT for additional information.
•
ROM
•
ROM
Address
Space
ROM
is
used as a memory for the instructions and the pat-
terns (constants). The instruction used in the
HMCS46C
consists
of
10 bits. These 10 bits are called
"a
word", which is a unit
for writing into
ROM.
The
ROM
address has been split into two banks.
Each bank is composed
of32
pages (64 words/page) .
The
ROM
capacity is 4,096 words
(1
word = 10 bits) in all.
All
addresses can contain
both
the instructions and the pat-
terns (constants).
The
ROM
address space
is
shown in Figure I.
1-----
64
words----i
1FOF
_3E3F
·Subroutine
Space
1
1o
.""
(1
Page)
I
1\(
I
I
I
I
I
I
I
I
I
,
(30
Page)
(31 Page)
(32 Page)
(33 Page)
I
I
I
I
I
I
I
I
(61
Page)
(62 Page)
E (63 Page)
·Bank
0 0 Page (0 Page)
is
the
Subroutine Space.
Timer/Counter Interrupt Address
Bank
0 0 Page
3F
Address
(0 Page
3F
Address)
Input
Interrupt Address
Bank
0 1 Page
3F
Address
(1
Page
3F
Address)
Reset Address
Bank 1
31
Page 3F Address
(63 Page 3F Address)
Note:
The
parenthesized
contents
are expressions
of
the Page, combining
the
bank
part
with
the
page part.
Figure 1
ROM
Address Space
89
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