Today I noticed that “74253” and the “74LS253” schematic symbols look very different.
Also the “74164” and the “74HC164” schematic symbols look very different.
Also the “74153” and “74LS153” schematic symbols look very different.
Is there a specific reason they look so different? (Perhaps something related to the “74xx_IEEE” library versus the “74xx” library)?
Or were they merely drawn independently by two different people that didn’t really intend to make them look different?
I expected them to be aliases and therefore identical-looking in exactly the same way that the “7400” is an alias of the “74LS00” symbol.
(I’m designing something that uses a bunch of 74HC253 muxes, with perhaps some 74F253 muxes in speed-critical areas. Neither one of these exact part numbers is in the KiCad default symbol libraries, but the symbol should be the same as the 74253 symbol – or should I be using the 74LS253 symbol?).
(I’m currently using KiCad Version: 5.99.0-unknown-5975524826~131~ubuntu20.04.1, release build
if that’s relevant).