Holtek HT827A0 Manual page 11

I n d i r e c t A d d r e s s i n g R e g i s t e r
0 0 H
M P
0 1 H
0 2 H
0 3 H
0 4 H
0 5 H A C C
P C L
0 6 H
T B L P
0 7 H
T B L H
0 8 H
W D T S
0 9 H
0 A H S T A T U S
I N T C
0 B H
0 C H
0 D H
0 E H
T M R H
0 F H
T M R L
1 0 H
T M R C
1 1 H
P A
1 2 H
P A C
1 3 H
1 4 H P B
1 5 H P B C
1 6 H P C
P C C
1 7 H
1 8 H P D
1 9 H P D C
1 A H P E
1 B H P E C
1 C H
1 D H
1 E H
1 F H
D A L
2 0 H
D A H
2 1 H
V C R
2 2 H
2 3 H S R C
2 4 H
2 5 H
2 6 H
2 7 H
2 8 H B E A T
2 9 H T E M P O
2 A H T O N E
2 B H
2 C H R O M C
2 D H
2 E H
2 F H
3 0 H
G e n e r a l P u r p o s e
D A T A M E M O R Y
F F H
RAM mapping
control registers (PAC; 13H, PBC; 15H, PCC;
17H, PDC; 19H, PEC; 1BH). The 20H to 2FH
are used for sound and tone (melody) synthesis.
The function registers include a lower-order
byte register (DAL; 20H) of D/A data,
higher-order byte register (DAH;21H) of D/A
data , volume control register (VCR; 22H), sam-
pling rate control register (SRC; 23H), beat con-
trol register (BEAT; 28H), tempo control
register (TEMPO; 29H), tone control register
(TONE; 2AH) and voice ROM control register
(ROMC; 2CH). The remaining space before 30H
is reserved for future expansion. Reading these
remaining locations will get ²00H². The general
purpose data memory is used for data and con-
trol information under instruction commands.
All of the areas of data memory can handle
arithmetic, logic, increment, decrement and ro-
tate operations directly. Except for some dedi-
S p e c i a l P u r p o s e
cated bits, each bit in the data memory can be
D A T A M E M O R Y
set and reset by ²SET [m].i² and ²CLR [m].i²,
and can also be indirectly accessed through a
: U n u s e d
memory pointer register (MP; 01H).
R e a d a s " 0 0 "
Indirect addressing register
Location 00H is an indirect addressing register
that is not physically implemented. Any
read/write operation of [00H] accesses the data
memory pointed to by MP (01H). Indirectly read-
ing location 00H will return the result to 00H
whereas, indirectly writing it will have no effect.
Arithmetic and logic unit - ALU
This circuit performs 8-bit arithmetic and logic
operations. ALU provides the following func-
tions:
· Arithmetic operations (ADD, ADC, SUB,
SBC, DAA)
· Logic operations (AND, OR, XOR, CPL)
· Rotation (RL, RR, RLC, RRC)
·
Increment & decrement (INC, DEC)
·
Branch decision (SZ, SNZ, SIZ, SDZ ....)
ALU not only saves the results of a data opera-
tion but also change the status register.
11
HT827A0
March 15, 2000