7 Jan
2005
7 Jan
'05
4:52 a.m.
Hi
Most of these were designed such that a single
output pullup resistor didn't use all of the
sink of an output transistor. This means that
two outputs tied together and would not draw too much
current.
DTL does the same thing and allows the wired AND.
As I recall, with RTL, you only needed to apply
power to one device if they were inverters
since there was no other active logic,
like flops.
Dwight
From: "Steve Thatcher"
<melamy(a)earthlink.net>
I don't see how doing a wired-and is possible when RTL includes a pullup
resistor on each output. You would get to a point where an individual output
transistor would not be capable of sinking all the "low" current.
You can get a basic idea of the logic families here...
http://www.asic-world.com/digital/gates5.html
best regards, Steve Thatcher
-----Original Message-----
From: "Dwight K. Elvey" <dwight.elvey(a)amd.com>
Sent: Jan 7, 2005 12:22 PM
To: cctalk(a)classiccmp.org
Subject: RE: RTL Logic
Oops!
I forgot one thing. You can put several RTL outputs in
parallel as a wired AND. You can't do that with the
general CMOS or TTL. You'd need to look out for this.
Does anyone have a source for DTL parts. There are
a could I've been looking for.
Dwight