> I booted into MacOS and only 8 MB showed up in the About This Macintosh 
window. 
> Now, these SIMMs have worked just fine for years in the IIsi and are working 
just fine 
> now in the IIcx after that initial weird boot.

I suspect that the "Mode 32" extension was not yet active.  In 24 bit 
mode, 8MB is the maximum allowed memory.  "Mode 32" allows you to run in 
32 bit mode on some machines which are not "32 bit clean".

...Harlan