TTL HEX LED driver chip

I see... For those who are wondeirng, the 'trivial' solution I mentioned uses 7 off 74150 16-input multiplexers, one for each segment. You tie the inputs high low to determine if that segment is on or off for a given set fo 4 input bits. After posing that, I thought of other solutions that make no assumptions about the segment patterns -- they always work. For example 7 off 74151 8 input muxes and a single inverter (1/6 of a 7404) That has the advantage of automatically providing actrive high and active low outputs. Or use a 74154 to decode the input bits and then logically OR the active low outputs together with 7430 8-input NANDs. The thing is that a given segment is either on in 8 or fewer patterns or it's off in 8 or fewer patterns (it must be one or the other since there are only 16 patterns). So you can get away with 8 input NAND gates, maybe you need to invert the outputs (7404s again) [1]. So that's 9 packages (74154, 24 pin, 7 off 7430, 14 pin and a 7404, also 14 pin. If you need to invert all 7 putputs, and thus need more than the contents of a 7404, then I would simply redefine the problem to use the other type of display :-). Actually, in all cases you probably want some kind of driver on the outputs, so you can pck a normal or inverting onme. I've not writtne down the turth table so I don't know if you can use smaller NAND gates for some of the outputs, and thus get away with fewer packages. Anyother thought I had is to use a 7447 for the lower 8 or 10 patterns (as it's designed to do!) and add logic for the higher ones. I don't know if that saves chips. [1] I beleive you need this sort of trick to build such a decoder in a stnadard PAL or GAL device. -tony