You are currently viewing SemiWiki as a guest which gives you limited access to the site. To view blog comments and experience other SemiWiki features you must be a registered member. Registration is fast, simple, and absolutely free so please, join our community today!
Looking at that schematic I would expect unconnected inputs to float high. If there isn’t any current flowing through one of the diodes to pull down the 20k resister then the input will be pulled up to a diode drop below the rail. That’s a solid high level.