They have a 16 Mhz 68020 and math coprocessor onboard, along with 4M of RAM. They also have the wretched Intel ethernet controller.
They are nice to work with (compared to something like the Sun 3/260) because they have their own RAM onboard and a single board makes a working computer.
Schematics are now available online. Their utility will be limited because the board uses a large number of programmable logic devices. I count 37 PAL and HAL devices on the board I have, along with 4 bipolar ROM devices. Any effort to understand the design won't go far without knowing what each of these devices does.
I have not yet tried to read out any of these devices. If the security fuse is blown, the problem becomes much more difficult and perhaps impossible.
Tom's Computer Info / tom@mmto.org