Designing a 16-4 priority encoder from 2 74148 8-to-3 line priority encoder device

Thread Starter


Joined Sep 21, 2008
Hi all,

My tutor gave me an answer I did not understand.
I searched the datasheet of 74148 but it did not specify what is GS, E0 and E1.

I also do not understand why the E1 of one 74148 is connected to the E0 of another.

Can anyone help?


Joined Apr 20, 2004
All you have to do is look at the truth table to see what conditions set GS low and EO low. You can also see the effect of the EI^ input (hint - when it is high, what happens to the outputs, including GS^ and EO^?).

Thread Starter


Joined Sep 21, 2008
Well, I got the answer from my tutor but there is one thing I dont understand. What does GS stands for?

I learnt from my tutor that:

1) The IC that displays the MSB have to be disabled if it is below a certain level.

2) The outputs from each gate have to be AND together to produce the desired output.

I know that E is enable while I0 to I7 are the inputs while thost starting with A are the outputs.
And I still dunno what GS stands for? :confused:


Joined Feb 19, 2009
GS is "Group Output" - goes low on priority detect, with priority address in A0-3, also active low, combined with GS to flag which IC when cascading two.