ON 20030220@8:09:30 AM at page: http://massmind.org/techref/logic/TTLs.htm DAV-MP-E62a David A Cary Says /techref/logic/family.htm (up) ON 20030220@8:21:31 AM at page: http://massmind.org/techref/logic/TTLs.htm DAV-MP-E62a David A Cary Says http://www-s.ti.com/sc/ds/sn7400.pdf Figure 3 is not yet accurate.
nit: the bottom (emitter) of the lower transistor connects directly to ground, there is no resistor there.
typo: the output of 7400 connects directly to the top (collector) of the grounded transistor. It does not connect to the bottom (emitter).

Hope that helps. ON 20030220@4:20:03 PM at page: http://massmind.org/techref/logic/xtrapins.htm DAV-MP-E62a David A Cary I have agreed to maintain this page. ON 20030220@4:21:38 PM at page: http://massmind.org/techref/logic/xtrapins.htm DAV-MP-E62a David A Cary edited the page. Difference: http://massmind.org/techref/diff.asp?url=H:\techref\logic\xtrapins.htm&version=1 ON 20030220@4:23:05 PM at page: http://massmind.org/techref/logic/xtrapins.htm DAV-MP-E62a David A Cary edited the page. Difference: http://massmind.org/techref/diff.asp?url=H:\techref\logic\xtrapins.htm&version=2 ON 20030221@4:09:06 PM at page: http://massmind.org/techref/logic/xtrapins.htm DAV-MP-E62a David A Cary edited the page. Difference: http://massmind.org/techref/diff.asp?url=H:\techref\logic\xtrapins.htm&version=3