[sci.electronics] Help with 74LS688 chip

nsus_cif@troi.cc.rochester.edu (Nick Susch) (04/03/91)

Hi, I am working on a project that uses the 74LS688 chip. Unfortunately,
I can't find this chip or any information on it, anywhere in Rochester.
The schematics I am useing to wire it up also don't say anything about
the pin-outs of it. It is called an "8-bit comparitor" and looks like it
is used to compare two 8-bit numbers (brilliant deduction, huh? :-) Well,
to make this story short, I can easily get two 74LS85 chips (4-bit
magnitude comparitors), the only thing is, I need the pin-out of the
74LS688 so I can find out what the functions of the outputs are (low when
=, or high, etc...)  So can someone who knows the pinout and functioning
of the 74LS688 please e-mail it to me? It would be greatly appreciated.
Thanks!

--
"And when I have understanding    |   /\/ick Susch - University of Rochester
 of computers, I will be the      |   nsus_cif@uhura.cc.rochester.edu
               supreme being!"    |   nsus_cif@uordbv.bitnet
  - Evil (from "Time Bandits")    |   ... !rochester!ur-cc!nsus_cif

andreww@uniwa.uwa.oz (Andrew John Williams) (04/03/91)

The pinout for the 74LS688 is:

  -G 1   20 Vcc
  P0 2   19 -(P=Q)
  Q0 3   18 Q7
  P1 4   17 P7
  Q1 5   16 Q6
  P2 6   15 P6 Qi
  Q2 7   14 Q5
  P3 8   13 P5
  Q3 9   12 Q4
 GND 10  11 P4

sorry if that looks a mess. I made a mistake on pin 15 (it should be P6)
and since I never really learnt VI all that well I don' know if I fixed
it or not. But anyway. How old is your TTL book? My '86 ALS/AS book has
it, and I'd guess it was LS for a while before then (I've just had a
closer look at the page. Down the bottom it says (c) 1982 Texas
Instruments. How old IS your TTL book?!?

John West (stealing Andrew's account)
and running out of foolish fish quotes