SPC = Small Peripheral Controller. Typically these
are quad or hex
hight cards. Quad cards go into C-F. So they can occupy the same
physical slot as say an M9202 (or a terminator). Hex cards must go into
a slot all by themselves (duh).
A very minor correction : I've got some 3rd party hex-height SPC cards
(The interfacae for the I2S Model 70 image display, for example) that
have a rectangular cutout where the A-B connectors would be. That will
fit over an M920 jumper or M930 terminator (but not, of course, the
longer M9302 terminator), so this card can go in the 'end' slot of a
backplane.
-tony