Am 21.05.2010 10:18, schrieb Invisible:

> The datasheet for the 7400 is 1 page. It tells you the maximum voltages
> and currents, a few time constants, and that's literally *it*.

I guess you're talking about the Texas Instruments Digital Logic Pocket 
Data Book; I must confess that I lied to you about that: It only 
contains summaries of the actual datasheets. For each individual device, 
TI has much more detailed documentation; for instance, the datasheet for 
the SN54HC00/SN74HC00 alone is 18 pages in total.

> As I say, it's not a manual. It assumes that you already *know* what a
> NAND gate is (which fortunately I do).

Yes, the Pocket Data Book does indeed assume you already have some 
/general/ idea what each of the devices (or at least the subset thereof 
that you're interested in) does.

So do the datasheets. Still they're manuals (and often better at that 
than most software documentation) - but remember that a manual does not 
necessarily include a tutorial.

> I have no idea how or why transistors work. But then, the entire _point_
> of a logic gate is that it doesn't matter _how_ it works. It's a black
> box. It implements a logical function. That should be all you need to know.

Note however that this black-box-knowledge should include the interface 
characteristics - and knowing what goes on in a /simple/ logic gate 
helps a lot to this end.

For instance, you should know how many inputs a logic gate output can 
drive reliably; how an unconnected input behaves; how the gate creates, 
and how it is affected by, noise on the power rails (and how to deal 
with that phenomenon); how much current the gate draws, and what 
parameters affect the power consumption (e.g. a TTL device will draw 
current primarily due to its internal state, while a CMOS device will 
draw current primarily due to changes of its internal state); and plenty 
more such stuff.

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