From: Magnus Eriksson (mage2254_at_thedreamer.nospammail.net)
Date: 2005-10-14 19:11:32
On Fri, 14 Oct 2005, Baltissen, GJPAA (Ruud) wrote:
> I need a 1-to-2 demultiplexer and then every input must be set
> seperately. I think it simply doesn't exist and found out that
> the next easiest way is to take two 74LS139 who can provide the
> four 'elements' I need.
"Every input"? You have one input for the signal to be routed, and
one input for selecting where it goes, right?
It seems to me that a 1-to-2 demux is such a simple building block
that most people would prefer building their own from gates. A
quad-NAND would do nicely in your case (if my assumption is right,
and your mentioning a '139 is just the drugs talking):
+------------|-.________
___ | +-|-' ROM CS
ROM/RAM sel | |
-------------+-=| )-------|-.________
___________ +-|-' RAM CS
chip select |
---------------=| )-----+
^
signal connected to both inputs, so = inverter
Or I could just have misunderstood what you meant, YMMV, IANAEE
(yet), etc. Surely you would only need half (or "a quarter") of a
139 for this, and not two?
> ___
> / __|__
> / / |_/ Groetjes, Ruud
> \ \__|_\
> \___| URL: Ruud.C64.org
Your ASCII skillz are obviously better than mine. :-)
MAgnus
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