🚀 go-pugleaf

Gary  huntress (ghuntres@nyx.cs.du.edu) wrote:
: 
: Can LS, ALS, and CMOS (pin compatible) components be substituted
: for TTL parts in general?  I've got an "old" TTL system that needs
: a couple of spare parts, do I need to agonize over speed, power, fan out
: rise times.......or are the newer logic families always "better"?
: 


Hi Gary

In most cases you can. Simply choose one of the following

    1. Just try.
    2. Have a look at the introduction of a logic data book
       such as National or (.. what ever).

Be careful with 74Fxx types. They produce very sharp edges and can
cause trouble. For all common applications LS, ALS, HCT are equivalent
and ok. 

The TTL and CMOS mix works from CMOS output to TTL input, but not vice
versa. (In fact it may work, but there is no guarantee, so forget about.)


juerg at ethz switzerland