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DECODE32, 64

32- and 64-Bit Active-Low Decoders

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

figures/x8203.gif

figures/x8204.gif

DECODE32 and DECODE64 are 32- and 64-bit active-low decoders. In XC5200, decoders are implemented by cascading CY_MUX elements driven by lookup tables (LUTs). When one or more of the inputs are Low, the output is Low. When all the inputs are High, the output is High. You can decode patterns by adding inverters to inputs. Pull-ups cannot be used on XC5200 longlines.

In Virtex, decoders are implemented using combinations of LUTs and MUXCYs.

Refer to the “DECODE4, 8, 16” section for a representative schematic.

Inputs
Outputs
A0
A1

Az
O
1
1
1
1
1
0
X
X
X
0
X
0
X
X
0
X
X
X
0
0
z = 31 for DECODE32; z = 63 for DECODE64

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