On 19-5-2010 13:07, Invisible wrote:
> 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!

I think I resist any urge to comment on this. Other than "RTFM" and "buy 
any 'electronics for dummies book'" before embarking on such a project.

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