Ah yes. That's the fun thing about doing digital electronics. You can't 
just *buy* a 7400. No, you have to decide whether you want a 74LS00 or a 
74HC00 or a 74HCT00 or...

Reading the datasheets is like walking into another world. (Especially 
since the datasheets are usually poorly-scanned grainy PDFs that don't 
match the part number you actually asked about!)

However, I just found the following pages:

http://www.kpsec.freeuk.com/components/ic.htm#logic
http://www.kpsec.freeuk.com/components/74series.htm
http://www.kpsec.freeuk.com/components/cmos.htm

Suddenly everything seems so much clearer. For example...

"74LS series: Inputs 'float' high to logic 1 if unconnected."

Oh crap. Well that would explain a thing or two! >_<

(I foolishly assumed that being unconnected would register as 0V - i.e., 
logic 0. Damn, this is going to make interactive testing *so* much harder!)

Also, it's nice to have some indication of the power requirements, 
switching frequencies, and what the hell all the letter codes mean!

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