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264 CHAPTER 6 / NONARITHMETIC COMBINATIONAL LOGIC DEVICES

n HD D u c L i o o
U i L J I J IJ I U 1

(a)

Inputs Segment Outputs

Bl A B C D a b c d e f g
0 X X X X 000000 0
1000 0 111111 0
1000 1 011000 0
1001 0 110110 1
1001 1 111100 1
1010 0 011001 1
1010 1 101101 1
1011 0 001111 1
1011 1 111000 0
1100 0 111111 1
1100 1 111001 1
1101 0
1101 1
1 1 1 6"0
1110 1
1111 0
1111 1

(b) (c)
FIGURE 6.22
Near-minimum design of a BCD-to-seven-segment converter, (a) Display format and the ten decimal
digits, (b) Truth table with a blanking input and without FDR. (c) EV K-niaps for the seven-segment
outputs showing near-minimum POS cover as given by Eqs. (6.18).

c(L) = [BCD](L)
BCD](L) (6.19)

f(L) = [CD + ABD + BC](L)

and are implemented in Fig. 6.24, where the active low blanking input BI(L) is realized by
using inverting tri-state drivers with active low controls as in Fig. 3.8d. Thus, Bl serves to