do 16-input nand gates exist?

You can tie your 16 logic inputs to the 16 input pins of two ea. 2 X 4- input AND gate ICs like the 74HC21. Those 4 outputs can then be NANDed together by tying those 4 outputs to the 4 input pins of a 4- input NAND gate, available as the 74HC20 (2 gates per IC). That output is the logical equivalent of NANDing all 16 of your inputs. If any of your 16 inputs go low, your output will go high.

Simple combinational logic can give you a workable solution from standard logic ICs you can get off the shelf. Two real 14-pin ICs instead of the one ideal but non-existent 20-pin IC.

Good luck Chris

Use 2, 8 input types that drive a AND type..

Pick your poison.

1. They do not exist.

1. Try this: (View in Courier)

.Vcc>-------------+ . | . [R] . | | \\ .IN1>----[--->OUT . | | / . . . . . . . | .IN16>---[

They used to exist (one gate delay and sixteen NAND inputs), in the form of TTL "expandable gates"; SN7423, SN7455, SN7460 and such. You would use an output (OR-INVERT section) with any number of input expanders (AND sections), to make a composite AND-OR-INVERT gate that had the same gate delay as a NAND or NOR. To make a 16-input NAND, use two SN7460 expanders and a single section of SN7423.

The signal from the expanders to the output section wasn't TTL-level, though.

Modified to save one part:

MooseFET wrote:

The solution: