Logic with transistors - reduce digital outputs

Forum 2005-2010 (read only) Hardware Interfacing
1

I need to control 6 inputs on a circuit, over a cycle of 3 steps. I can do it by using 6 digital outputs, but I wondered if any electronics guru's (I'm a newbie) could advise on how to reduce the output count with some clever logic trickery. Transistors would be nice, but there's a maplins nearby, so I can purchase some 74xx or whatever if needed.
The required states are :

Cycle a1 a2 b1 b2 c1 c2
T1 1 0 0 1 0 0
T2 0 0 1 0 0 1
T3 0 1 0 0 1 0

Obviously, it would be nice to avoid using 6 digital outputs - any bright sparks?

David

2

Of course you can generate any logic sequence with TTL.

But the sequence you want appears to be only three states so why not connect one output to a1 and b2, one to b1 and c2 and the third to a2 and c1.

3

Duh.
Pattern blindness.
I was looking at a version of that table in my notebook, and I was thrice damned if I could see a regular pattern that I could drive on three outputs!. Thanks very much pointing out what should have been obvious.

David