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X74_147

10- to 4-Line Priority Encoder with Active-Low Inputs and Outputs

XC3000
XC4000E
XC4000X
XC5200
XC9000
Spartan
SpartanXL
Virtex
Macro
Macro
Macro
Macro
Macro
Macro
Macro
N/A

figures/x4166n.gif

X74_147 is a 10-line-to-BCD-priority encoder that accepts data from nine active-Low inputs (I9 - I1) and produces a binary-coded decimal (BCD) representation on the four active-Low outputs A, B, C, and D. The data inputs are weighted, so when more than one input is active, only the one with the highest priority is encoded, with I9 having the highest priority. Only nine inputs are provided, because the implied “zero” condition requires no data input. “Zero” is encoded when all data inputs are High.

Inputs
Outputs
I9
I8
I7
I6
I5
I4
I3
I2
I1
D
C
B
A
1
1
1
1
1
1
1
1
0
1
1
1
0
1
1
1
1
1
1
1
0
X
1
1
0
1
1
1
1
1
1
1
0
X
X
1
1
0
0
1
1
1
1
1
0
X
X
X
1
0
1
1
1
1
1
1
0
X
X
X
X
1
0
1
0
1
1
1
0
X
X
X
X
X
1
0
0
1
1
1
0
X
X
X
X
X
X
1
0
0
0
1
0
X
X
X
X
X
X
X
0
1
1
1
0
X
X
X
X
X
X
X
X
0
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1

Figure 11.6 X74_147 Implementation XC3000, XC4000, XC5200, XC9000, Spartans

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