To implement a circuit we have a PAL requirement 4-input,4-output,(2,2,2,2) product terms.We are using a chip with 8 inputs,8 outputs(4 reg, 4non reg)(2,2,2,2,2,2,2,2). But it happened that we made a calculation error earlier and now find out that 1 of the output requires 3 product terms.Can it be possible to still implement the circuit using same chip by using leftover input and output pins.

  • \$\begingroup\$ Maybe I have I been away from academia too long, but, I'm not sure what "(2,2,2,2) product terms" means. Can you elaborate? Seems to me that the upper 4 inputs of the 8-8 could be tied to '0' and you are left with the 4-4(?) What are you trying to accomplish with your PAL in terms of a transfer function for the 4 inputs? \$\endgroup\$ – CapnJJ Jul 5 '18 at 5:21
  • \$\begingroup\$ @CapnJJ 2,2,2,2 is the no. Of product terms available for each OR gate. \$\endgroup\$ – Siddharth Jul 5 '18 at 11:33

If the timing doesn't matter you could connect one outputs to inputs. Say output 2 needs 3 product terms. You put term 1 and term 2 on output 5 and connect it to input 5. Then output 2 becomes input 5 or term 3.

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