<An FPF11 can be used with a KDF11-B (11/23+), which is a Qbus
<machine. It can also be used in an 11/24, it derives only
<power from the bus (if I remember correctly).
Correct, I have one.
<I would suspect that it might also work with an 11/23 (KDF11-A),
<since it has the same chip location for Floating point as the
<11/23+, but I've never confirmed this.
It works with all of the 11/23 series (Q and U,). Jumpers configure power
for either U or Q and much be checked before inserting.
What it is is a faster version on a quad board for the FPU chip. If you
crunch numbers on 11/23s or 11/24s it's a must have.
FYI, It's a raft of 2901s and some microcode to emulate the FPU chip.
It's faster as all the data paths internally (to the board) are wider.
Allison