HT82K68 Holtek Semiconductor Inc, HT82K68 Datasheet - Page 27

• Manufacturer Part Number: HT82K68
• Description: Multimedia Keyboard Encoder OTP
• Manufacturer: Holtek Semiconductor Inc

CPLA [m]
Description
Operation
Affected flag(s)
DAA [m]
Description
Operation
Affected flag(s)
DEC [m]
Description
Operation
Affected flag(s)
Complement data memory and place result in the accumulator
Each bit of the specified data memory is logically complemented (1¢s comple-
ment). Bits which previously contained a 1 are changed to 0 and vice-versa.
The complemented result is stored in the accumulator and the contents of
the data memory remain unchanged.
ACC ¬ [m]
Decimal-Adjust accumulator for addition
The accumulator value is adjusted to the BCD (Binary Code Decimal) code.
The accumulator is divided into two nibbles. Each nibble is adjusted to the
BCD code and an internal carry (AC1) will be done if the low nibble of the ac-
cumulator is greater than 9. The BCD adjustment is done by adding 6 to the
original value if the original value is greater than 9 or a carry (AC or C) is set;
otherwise the original value remains unchanged. The result is stored in the
data memory and only the carry flag (C) may be affected.
If ACC.3~ACC.0 >9 or AC=1
then [m].3~[m].0 ¬ (ACC.3~ACC.0)+6, AC1=AC
else [m].3~[m].0) ¬ (ACC.3~ACC.0), AC1=0
and
If ACC.7~ACC.4+AC1 >9 or C=1
then [m].7~[m].4 ¬ ACC.7~ACC.4+6+AC1,C=1
else [m].7~[m].4 ¬ ACC.7~ACC.4+AC1,C=C
Decrement data memory
Data in the specified data memory is decremented by1.
[m] ¬ [m] 1
TC2
TC2
TC2
¾
¾
¾
TC1
TC1
TC1
¾
¾
¾
TO
TO
TO
¾
¾
¾
Preliminary
PD
PD
PD
¾
¾
¾
27
OV
OV
OV
¾
¾
¾
¾
Z
Ö
Z
Z
Ö
AC
AC
AC
¾
¾
¾
¾
¾
C
C
C
Ö
HT82K68E
August 8, 2000