PAL implementation

4 – Combinational Logic Design Examples

© 1996 Gaetano Borriello

11

C0 = C3 + A' B X' + A D Y

C1 = Y + A' C5' + C' D' C6

C2 = C5 + A' B' D + A' C D

C3 = C4 + B D C5 + A' B' X'

C4 = D' Y + A' C D'

C5 = C' C4 + A Y + A' B X

C6 = A C4 + C C5 + C4' C5 + A' B' C

X = C' + D'

Y = B' C'

• Limit of 4 product terms per output

  • decomposition of functions with larger number of terms
  • do not share terms in PAL anyway(although there are some with some shared terms)
  • decompose into multi-level logic (hopefully with CAD support)
    • find common sub-expressions among functions

C2 = B + C' + D

C2 = B' D + B C' D + C' D' + C D + B C D'

C2 = B' D + B C' D + C' D' + W

W = C D + B C D'

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