HT47C20 datasheet(43/56 Pages) HOLTEK

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CPLA [m]

Complement data memory-place result in accumulator

Description

Each bit of the specified data memory is logically complemented (1 s

complement). Bits which previously contained a one are changed to zero

and vice-versa. The complemented result is stored in the accumulator

and the contents of the data memory remains unchanged.

Operation

ACC ¬ [m]

Affected flag(s)

TC2 TC1

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DAA [m]

Decimal-Adjust accumulator for addition

Description

The accumulator value is adjusted to the BCD(Binary Code Decimal)

code. The accumulator is divided into two nibbles. Each nibble is ad-

justed to the BCD code and an internal carry (AC1) will be done if the low

nibble of the accumulator 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.

Operation

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

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

Affected flag(s)

TC2 TC1

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DEC [m]

Decrement data memory

Description

Data in the specified data memory is decremented by one.

Operation

[m] ¬ [m]-1

Affected flag(s)

TC2 TC1

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HT47C20

January 18, 2000

HT47C20 Fiches technique(PDF) 43 Page - Holtek Semiconductor Inc

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