HT36A1
erwise, the sample will not be read out correctly be-
cause it has a wrong starting code.
purpose data memory, addressed from 30H to FFH, is
used for data and control information under instruction
command.
Stack Register - Stack
All data memory areas can handle arithmetic, logic, in-
crement, decrement and rotate operations directly. Ex-
cept for some dedicated bits, each bit in the data
memory can be set and reset by the ²SET [m].i² and
This is a special part of the memory which is used to
save the contents of the program counter (PC) only. The
stack is organized into 8 levels and is neither part of the
data nor part of the program space, and is neither read-
able nor writeable. The activated level is indexed by the
stack pointer (SP) and is neither readable nor writeable.
At a subroutine call or interrupt acknowledgment, the
contents of the program counter are pushed onto the
stack. At the end of a subroutine or an interrupt routine,
signaled by a return instruction (RET or RETI), the pro-
gram counter is restored to its previous value from the
stack. After a chip reset, the SP will point to the top of the
stack.
0
0
0
0
0
0
0
0
0
0
0
1
2
3
4
5
6
7
8
9
H
H
H
H
H
H
H
H
H
H
I
n
d
i
r
e
c
t
A
d
d
r
e
M
e
M
s
s
i
n
g
R
e
g
i
s
t
e
r
0
P
0
I
n
d
i
r
e
c
t
A
d
d
r
s
s
i
n
g
R
e
g
i
s
t
e
r
1
P
1
A
C
C
P
C
L
T
B
L
P
T
B
L
H
W
D
T
S
S
T
A
T
U
S
0
0
A
B
H
H
If the stack is full and a non-masked interrupt takes
place, the interrupt request flag will be recorded but the
acknowledgment will be inhibited. When the stack
pointer is decremented (by RET or RETI), the interrupt
will be serviced. This feature prevents stack overflow al-
lowing the programmer to use the structure more easily.
In a similar case, if the stack is full and a CALL is subse-
quently executed, a stack overflow occurs and the first
entry will be lost (only the most recent eight return ad-
dress are stored).
I
N
T
C
0
1
0
C
H
H
T
M
R
0
L
0
D
S
D
p
e
c
i
a
l
P
u
r
p
o
s
e
T
M
R
C
0
E
H
a
t
a
M
e
m
r
o
y
0
F
H
T
M
R
1
L
1
1
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
8
9
H
H
H
H
H
H
H
H
H
H
T
M
R
C
P
P
A
B
P
P
A
B
C
C
P
C
P
C
C
Data Memory - RAM
The data memory is designed with 256 ´ 8 bits. The data
memory is divided into three functional groups: special
function registers, wavetable function register, and gen-
eral purpose data memory (208´8). Most of them are
read/write, but some are read only.
1
1
A
B
H
H
P
F
1
C
H
D
A
C
H
i
g
h
B
y
t
e
(
D
A
H
)
1
D
H
1
E
H
D
A
C
L
o
w
B
y
t
e
(
D
A
L
)
1
F
H
H
H
H
H
H
H
H
H
H
H
D
A
C
C
o
n
t
r
o
l
(
D
A
C
)
The special function registers include the Indirect Ad-
dressing register 0 (00H), the Memory Pointer register 0
(MP0;01H), the Indirect Addressing register 1 (02H), the
Memory Pointer register 1 (MP1;03H), the Accumulator
(ACC;05H), the Program Counter Lower-byte register
(PCL;06H), the Table Pointer (TBLP;07H), the Table
Higher-order byte register (TBLH;08H), the Watchdog
Timer option Setting register (WDTS;09H), the Status
register (STATUS;0AH), the Interrupt Control register
(INTC;0BH), the Timer Counter 0 Lower-order byte reg-
ister (TMR0L;0DH), the Timer Counter 0 Control regis-
ter (TMR0C;0EH), the Timer Counter 1 Lower-order
byte register (TMR1L;10H), the Timer Counter 1 Control
register (TMR1C;11H), the I/O registers (PA;12H,
PB;14H, PC;16H) and the I/O control registers
(PAC;13H, PBC;15H, PCC;17H). The program ROM
bank select (PF;1CH). The DAC High byte (DAH;1DH).
The DAC low byte (DAL;1EH). The DAC control
(DAC;1FH). The wavetable function registers is defined
between 20H~2AH. The remaining space before the
30H is reserved for future expanded usage and reading
these locations will return the result 00H. The general
2
2
2
2
2
2
2
2
2
2
0
1
2
3
4
5
6
7
8
9
C
h
a
n
n
e
l
N
u
m
b
e
r
S
e
l
e
c
t
(
C
H
A
N
)
F
r
e
q
u
e
n
c
y
N
u
m
b
e
r
H
i
g
h
B
y
t
e
(
F
r
e
q
N
H
)
W
a
v
e
t
a
b
l
e
F
r
e
q
u
t
e
n
c
y
N
d
u
m
b
e
r
L
o
w
B
y
y
l
t
t
(
e
(
F
r
e
q
N
L
)
F
R
u
n
c
t
i
o
n
S
a
r
t
A
d
r
e
s
s
H
i
g
h
B
y
t
e
(
A
d
d
r
H
)
e
g
i
s
t
e
r
S
t
a
r
t
A
d
d
r
e
m
s
s
L
o
w
B
y
t
e
(
A
d
d
r
L
)
R
e
p
e
a
t
N
u
b
e
r
H
i
g
h
B
y
t
e
(
R
e
H
)
R
e
p
e
a
t
N
u
m
b
e
r
L
i
o
w
B
e
(
R
e
L
)
C
o
n
t
r
o
l
R
e
g
s
t
e
r
(
E
N
V
)
L
e
f
t
V
o
l
u
m
e
C
o
n
t
r
o
l
(
L
V
C
)
2
2
A
B
H
H
R
i
g
h
t
V
o
l
u
m
e
C
o
n
t
r
o
R
V
C
)
2
F
H
H
3
0
:
U
n
u
s
e
d
.
R
e
a
d
a
s
"
0
0
"
G
e
n
e
r
a
l
P
u
r
p
o
s
e
D
a
t
a
M
e
m
o
r
y
(
2
0
8
B
y
t
e
s
)
F
F
H
RAM Mapping
Rev. 1.00
8
August 15, 2005
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
