IIRC, there's a red herring out there about L2 Cache being present on the IIsi MoBo. It's a web site/article/whatever I've seen somewhere recently. Found it, researched it in different lists of specifications, debunked it and moved on w/o even looking at the components on my MoBo.

There are four ICs of some sort on the IIsi MoBo boxed in a graphic and identified as being L2 Cache, they certainly are not . . .

. . . now I'm curious . . . but very tired. |)

Did you take a peek at a NuBus adapter and see the stunted U in the designation for component U2? Looks to be part of a trace interfering with the printing.