New subject: misleading subject lines- vaxes, soldering, electricution, etc...

4 Oct 2007

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Subject: Re: these RTL or what?
   From: "Roy J. Tellason" <rtellason at verizon.net>
   Date: Thu, 04 Oct 2007 01:38:08 -0400
     To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>

On Tuesday 02 October 2007 09:56, Allison wrote:
  Subject:
these RTL or what?
   From: "Roy J. Tellason" <rtellason at verizon.net>
   Date: Tue, 02 Oct 2007 02:01:29 -0400
     To: "General Discussion: On-Topic and Off-Topic Posts"
 <cctalk at classiccmp.org>

I ran across some data in the pile of what I've been collecting,  and
 there's some stuff there apparently by Signetics (?) referring to what
 they're calling "Utilogic II" -- is this stuff RTL or what?  It
doesn't
 say.  Dates are in the late 1960s,  and it looks like it,  but I figured
 I'd ask in here... 
 There are many early families of saturated logic RTL is the oldest, 
Which explains why I was seeing it first,  and hobby-type projects based on it 
back when. 

The big thing of DTL was to add diodes to the input of the basic RTL structure
for increased (noise immunity) input thresholds for better noise immunity.  
Both families were easily wired OR and systems built around it usually 
exploited that feature.

...
   DTL and
it's kin "utilogic" where the intermediate sorta TTL like
 and later TTL( H,LS,S,F,AS,C,HC,HCT flavors). 
My first TTL book (which I still have) was a TI book that covered the 
standard, H, and L varieties.  LS and S I can understand,  F and AS still 
confuse me a bit,  I'm not quite sure where they fit in.  Then there are all 
those CMOS variants.  C parts are pretty uncommon these days,  and I'm not 
real clear on the distinction between HC and AC (I know about the ones with T 
in there,  just shifted thresholds on the inputs and I have a pile of 'em.)

  In the middle of all that was ECL (also about
three or four generations) a
 fast non saturating logic. 
I've read some ECL data,  but have never done a darn thing with it,  nor even 
seen much of anything that used it.  From what I understand it had some weird 
packaging sometimes,  very tight board layout requirements (I was mostly 
thinking of wire-wrapping stuff),  and was very power-hungry.  I guess if I 
ever want a prescaler for a counter to get *way* up there or maybe one or two 
other apps I can think of I might eventually have to go there,  depending on 
what parts I can find.  But I'm in no hurry.  :-) 
VAX9000 built of ECL100K, fastest of the fast.  The second most common 
use of TTL was in very high speed instrumentation and specifically frequency 
counters and UHF PLLs.

...
   What amazing
is when people say "60s" you must do so with care as
 1960 was basically germainium transistors but by 1964 silicon
 transistors are about and ICs were already appearing.  Most
 integrated circuit logic was post '65 and even then from that
 point speeds went from about 3mhz to 30mhz and RTL was replaced
 by TTL by 1970. 
I did say "late 1960s" up there.  :-) 
Even then.. ;)

It's hard to imagine the rate of change.  An example, Apollo Guidance Computer.
The AGC was designed too be built of RTL, by time it actually flew to the moon
is was actually a generation behind as TTL existed by then.  Of course that 
really was becase of development time being so long and space systems having
to be man rated (reliability assured). It was a case then of if it was out 
the door likely a whole new generation and technology was already in design.
Where commercial computers went from transistors  (1965ish PDP-5) to DTL 
and early TTL (1967ish PDP-8) in that same time window.  Computer design 
and packaging underwent significant change and not all of it was grossly 
obvious. 

...
   The
evoloutionary scale was very steep from the mid 50s to the mid 70s. 
 That 20 years window we went from computers with tubes to microprocessors,
 delays lines or other serial storage to semiconductor RAM. 
I remember seeing some of the boards from the tube stuff for sale in various 
electronic junk places around.  I may have even got one or two for parts,  
though there was nothing to be done with those backplane connectors.  I 
remember one set of 9-pin sockets for which it was apparent to me that they 
were using something like a 12AU7,  because of the center-tapped heater 
connections.  :-) 
Yep, back then those were good sources of parts for building radios.  Most 
however were noncomputer pulled from things like old instruments and the like.

Allison