MC14560BD 데이터 시트보기 (PDF) - Motorola => Freescale

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MC14560BD

NBCD Adder

Motorola => Freescale 

Inputs

AS

BS′

“1” = Neg “1” = Neg

0

0

0

0

0

1

0

1

1

0

1

0

1

1

1

1

* Output of Adders

Cout

“1” = Carry

Arithmatic Expression

for R* (Result)

(N = Number of Digits,

10N = Modulus

A, B, R are Positive

Magnitudes)

End Around

Carry (EAC)

“1” = EAC

Outputs

Sign of R

“1” = Negative

Overflow

“1” = Overflow

0

R=A+8

No EAC (“0”)

because R is correct

result.

Since A and B are

positive signed, R is

positive signed (“0”).

When Cout = “0”, there

is no carry (R < 10N)

and thus no overflow

(“0”).

When Cout = “1”, there

1

is a carry (R ≥ 10N)

and thus overflow

(“1”).

No EAC (“0”)

vA B when Cout =

0

R=A–B

because 9’s

“0”; thus sign of R

= A + (10N – 1 – B) complement

must be negative

= A – B + 10N – 1

expression for R is (“1”).

correct result.

EAC = “1” because A > B when Cout =

1

expression for R is in “1”; thus sign of R

error by 1.

must be positive

There is never an

0

R=B–A

No EAC (“0”)

because 9’s

(“0”).

vB A when Cout =

“0”; thus sign of R

overflow when

numbers of opposite

sign are added.

= B + (10N – 1 – A) complement

must be negative

= B – A + 10N – 1

expression for R is (“1”).

correct result.

EAC = “1” because B > A when Cout =

1

expression for R is in “1”; thus sign of R

error by 1.

must be positive

(“0”).

0

R=–A–B

EAC = “1” because

9’s complement

Since A and B are

When Cout = “0”, there

negative signed. R is is no Carry (R < 0N)

= (10N – 1 – A) +

expression for R is in negative signed (“1”). and (A + B) > 10N – 1

(10N – 1 – B)

error by 1.

indicating overflow

= – (A + B) + 2 x

10N – 2

1

(“1”).

When Cout = “1”, there

v is a carry (R ≥ 10N)

and (A + B) 10N – 1

indicating no overflow

(“0”).

Figure 9. Truth Table Generation for EAC, Sign, and Overflow Logic

MC14560B

10

MOTOROLA CMOS LOGIC DATA

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