Fully unrolled RC5 on FPGA

Gerald Richter <glassman1neonshadow.net> wrote:
> Erg, i've always been a not fan of kludges like that.
They work, and 
> very well for some things, but just ugh. Gimme a full
length PCI card 
> with a bridge chip, whatever other support logic is
needed and sockets 
> for like 8 chips and i'm happy. I dunno, how big are
the spartan 4? 
> Could we fit more spartan 3s in the space?

None of these devices which have a practical size are easily
socketed.
Most are ball grid arrays (BGA), or fine pitch quad flat
packs (QFP).
The price per performance doesn't favor a bunch of small
fpga's, but
may well favor a few mid to large sized fpga's.

As for card chassis, server PC's are still the cheapest, and
most usable
chassis ... far better than some VME kludge. A typical mid
end PII or
PIII PC server motherboard has a bunch of slots, including a
couple 64bit
3.3V PCI slots, can be had for small change. Some more
interesting boat
anchors, like older high end servers, typically have a large
number of
PCI slots (up to 12), including a large number of 64 bit
slots.

It might not be unreasonable to make a card so that it can
passively
occupy a 5V PCI slot (take power and mounting from it), but
not interface
to the 5V PCI. Or to put a 5V tollerant CPLD on a 5V PCI
card to pick
off ISA emulation I/O ports with a narrow (8/16) bit bus
width, as an
interface to the fpga array. Or, use some older XC4K fpga's
as the bridge
to the newer fast/cheap fpga's. 5V PCI capable XC4K parts
frequent Ebay
for chump change, as do the CPLDs.

John
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