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From: mark@mips.COM (Mark G. Johnson)
Newsgroups: sci.electronics
Subject: Re: A 74F74?
Message-ID: <37746@mips.mips.COM>
Date: 7 Apr 90 15:30:12 GMT
References: <9561@sdcc6.ucsd.edu>
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In article <9561@sdcc6.ucsd.edu> pa2384@sdcc13.ucsd.edu (G. Clark) writes:
>
>	Can someone tell me if a 74F74 is just a 74H74 in disguise?
>I've never seen 'F TTL before.  Is this Fairchild's high-speed TTL?
>What does the F stand for 'fast' or fairchild ;-)!

"FAST" == Fairchild's Advanced Schottky Technology.  It's a completely
new circuit family and a new more advanced semiconductor fabrication
process.  The circuit family uses a different internal arrangement of
transistors, diodes, resistors, and capacitors than the other TTL-like
families.  It isn't 74H or 74S or 74AS or 74ALS.  It's 74F.

Curious that you should mention 74H.  It was the speediest TTL for
only a very brief period.  74H used high currents and gold-doped
junctions for high speed, but the 74S family quickly appeared and
wiped 74H practically off the face of the earth.   74S is faster and
lower power than 74H.  And now 74F is faster still.  Life marches on.
A few parts from TI are even faster than 74F, but TI will gladly sell
you 74F as well; it's a "standard" you know.

Get a FAST databook from Signetics and read the intro chapters on
the circuit family.  Then post to the net an explanation of the
"Miller killer" (not making this up, honest) circuit within the gate
that makes 74F so doggone fast.
-- 
 -- Mark Johnson	
 	MIPS Computer Systems, 930 E. Arques, Sunnyvale, CA 94086
	(408) 991-0208    mark@mips.com  {or ...!decwrl!mips!mark}