[Premium-Rx] Jim Garland's MECL Chips

[Carcia, Francis A HS]

    MECL was ECL logic and required level shifters to interface TTL. They
usually ran at -5 volts and every output required a pull down resistor. This
was early high speed logic before HC and AC CMOS. MECL 1 was the first
family that goes back to the 60s. A lot of that stuff was flat pack or in
today's terms gull wing.  fc

-----Original Message-----
From: Geoff Fors [mailto:wb6nvh at mbay.net]
Sent: Monday, March 28, 2005 2:45 PM
To: premium-rx at ml.skirrow.org
Subject: [Premium-Rx] Jim Garland's MECL Chips


Jim,
 
All those Motorola MECL II chips are in the 1968 Motorola "Integrated
Circuit Data Book."
I can make you copies of the data pages on each of them if you wish, but
contact me off-list about that.  They are clocks and gates and flip-flops as
you surmised.  I don't have the spare time to scan and process them as
digital files, but I can photocopy them.
 
These chips were truly state of the art in the late 1960's but vanished when
TTL became the norm.  It's amazing how hard it is to find data on them these
days!
 
As I recall these early MC- prefixed devices are RTL and MECL use a 3 volt
VCC so you can't just swap some common TTL chip and expect it to work.  
 
Normally, troubleshooting something like this would involve a handful of
good chips, a bugtrap, maybe a scope and a Huntron Tracker, and a logic
probe, but you don't have the luxury of known good chips and I don't think
the Bugtraps work on MECL or RTL.  Oh yes, by the way, don't forget to check
for shorted electrolytics and tantalum match-head style capacitors.
 
This topic points out some of the difficulties intelligence agencies faced
when trying to reverse engineer pieces of equipment captured from "enemy "
nations.   Today, everything is full of Motorola, Intel or other western
name brand chips!
 
Geoff Fors  

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