re act others said s later modification of for even higher speed at some cost in power consumption effectively obsolete use f ls combination of l and s for speed comparable to with lower power consumption best all round ttl now widest variety of devices f fast as blazes power not too bad the clear choice for high speed in ttl availability and prices generally good i hate to disagree w a fellow as smart as henry but a few years back i worked on a project using lots of high speed stuff my part was slow parallel whew the mild mannered designer working on the fast serial stuff cussed swore at f all the time it was the harry reams of ttl one ultra tiny power line glitch one hickup one eyeblink across the board and bang the f had toggled counted whatevered at times he swore it would count even without any volt supply you can guess what the f stood for they would do anything to push s or work around it to avoid using f i don t think i d consider using f to replace s unless the consequences were fully understood a host is a host from coast to coast wb foz skybridge scl cwru edu no one will talk to a host that s close linux unless the host that isn t close pob is busy hung or dead
