Mac Classic logic board chips involved in start

[doctormistral]

Normally connecting a Mac Classic (working) logic board to only its Molex connector (so no ram card, no floppy, no disk), it starts with sound and showing the floppy with question mark on the screen.

Now, I'd like to know which components of LB are (not) participating in this phase in order to concentrate on them (or exclude them) in my tests to understand why it does not start.

Thanks for suggestions.