Build your own Apollo Guidance Computer
cclist at sydex.com
Tue Dec 19 20:57:19 CST 2006
On 19 Dec 2006 at 15:41, Guy Sotomayor wrote:
> LS usually has the speed of TTL with the power dissipation of L.
> Other variations:
74F is another common one. Normally, one can assume that the
pinout's the same between all families, regardless of the letters
after the "74". The notable exception is 74L--some members of the
family have pinouts that differ from the corresponding 74/74S/74LS
ones. e.g., 74L85 vs. 7485.
Similarly, 74 and 74-followed-by-alphabet-soup ICs can differ in
implementation. Some notable examples are 7473--positive pulse-
triggered JK FF; 74LS73 negative-edge-triggered JK FF.
And again, one could get away with wire-OR-in 74L-series logic, which
would be a disaster in any other 74-series logic family.
Just a gentle reminder to check the databook before cross-
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