RTL Logic

[Randy McLaughlin]

It's funny to have a good discussion based on projects published over 30 
years ago.

For the OP, modifying the original project to use currently available 
devices, especially if you use devices that were contemporaneous seems OK to 
me.  I would not be surprised if people used 7404's or 7406's to build some 
of these projects when they first came out.

I would be curious to know the reasoning of using RTL chips when TTL chips 
were available considering they are driven out of spec, maybe Don was just 
more comfortable with them or that is what he had laying around.


Randy


----- Original Message ----- 
From: "Dwight K. Elvey" <dwight.elvey at amd.com>
To: <cctalk at classiccmp.org>
Sent: Friday, January 07, 2005 12:52 PM
Subject: RE: RTL Logic


> 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 at 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 at amd.com>
>>Sent: Jan 7, 2005 12:22 PM
>>To: cctalk at 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