8 Mar
2011
8 Mar
'11
1:12 p.m.
On Tue, Mar 8, 2011 at 1:57 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> EAE was PDP-8
Yes and no. Yes, there is the Extended Arithmetic Element for the
-8/i and for the KK8E (-8/e/f/m) CPUs, but the KE11, available as the
KE11-A (multiple cards and "system module" (backplane) for the 11/20
and similar) and KE11-B (single M7840, for newer Unibus machines after
the transition to SPCs and such), was *also* called an EAE by DEC.
It's not a particularly common option for the PDP-11, so I can
understand the confusion.
(DEC notes from 1969 on the KE11-A)
http://www.bitsavers.org/pdf/dec/pdp11/memos/690613_PDP-11_EAE.pdf
Maybe I've mis-remeebred the name. There was a
hex-height Unibus board
(jsut one obard) that was a hardware integer multiplier and divider. It
was used with PDP11s that didn't ahve EIS (11/04, 1/05, etc) and it
required special software support. It didn't add to the processor
instruciton set, rahter you wrote the operands to particular I/O
addreses and read the results back in the same way.
Sounds like this...
(from http://www.psych.usyd.edu.au/pdp-11/early_peripherals.html)
"KE11 (EAE)
The Extented Arithmetic Element was a unibus peripheral that
implemented hardware multiply, divides, multiple shifts and fraction
normalisation. It was implemented as a number of registers in the I/O
page; you would write the operands into a set of eight registers. For
a multiply, simply loading the multiply register would initiate the
calculation. This device was mainly used on the PDP11/20 which lacked
a multiply and divide instructions (as did the /04, /05 and /10. "
I am pretty sure RT11 Fortran could use it.
The 1972 version of UNIX for the PDP-11/20 *required* it (
http://www.skytel.co.cr/unix-source-code/research/pups-mail/eml.1158.html
). For that reason, I've been keeping a casual eye out for either a
KE11-A or -B. I can't really afford a "market-rate" KE11-B from a DEC
reseller, so I haven't looked all that hard. Also, my 11/20 is still
in need of a serious amount of work (it was dismantled and binned
before I got it, so I have a *lot* of mechanical restoration to do
before I even dig into the state of the cards).
-ethan