From: Baltissen, GJPAA (Ruud) (ruud.baltissen_at_abp.nl)
Date: 2005-10-14 13:37:09
Hallo,
> 257 / 258?...
>
> > Sorry, it's indeed a dual 4-to-1 multiplexer and not a quad 2-to-1,
> > as I thought.
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.
Where do I need it for? The idea is to enable the user to choose between the
original ROM or a replacement RAM. The original input towards the ROM is fed
to the 139 and an output from a 6526 decides whether the original ROM is
selected or RAM. The RAM can be written and read by a 65816 in the $FFxxxx
area.
--
___
/ __|__
/ / |_/ Groetjes, Ruud
\ \__|_\
\___| URL: Ruud.C64.org
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