At 3:58 AM -0700 7/21/97, Decius 6i5 wrote:

I've been reading the Geodesic systems thread with much interest... I've been playing around with FPGAs recently, Field Programmable Gate Arrays, which list members should be familiar with due to discussions concerning cheap hardware crypto. Why not replace your entire architecture with reconfigurable hardware? This is sort of like Java turned upside down.

Why not replace your entire architecture with reconfigurable hardware? Because factors of 2 or 3 or 4 or more are still important to people. Witness the clamor to upgrade from 166 MHz Pentia to 200 MHz MMX Pentia, etc. Now tell those folks that the FPGA version will cost several times as much and have the performance of a 90 MHz 486. Or less. All for what? So they can issue a "reconfigure yourself" command and have their machine spend a few minutes reprogramming itself into, what, a Mac? For lots of reasons, this won't fly. I could elaborate on why this is so, technically, or marketing-wise. But I'll leave this as an exercise. One of the great breakthoughs of this century was the notion by von Neumann and others of a general purpose engine programmable with programs, instead of rearranging patch panel connections for each new algorithm. A general purpose CPU able to run NT, Linux, NextStep, OS/2, and myriads of programs is generally more useful to most people than (expensive) reconfigurable hardware. Except for specialized applications, which is where graphics accelerators, I/O processors, and digital signal processors (DSPs) come to the fore. However, even with these funcitons, as soon as these functions get integrated onto the main processor, as time passes, the handwriting is on the wall. (Look at what happened to Weitek once Intel and Sun integrated floating point coprocessors directly into their processors.) --Tim May There's something wrong when I'm a felon under an increasing number of laws. Only one response to the key grabbers is warranted: "Death to Tyrants!" ---------:---------:---------:---------:---------:---------:---------:---- Timothy C. May | Crypto Anarchy: encryption, digital money, tcmay@got.net 408-728-0152 | anonymous networks, digital pseudonyms, zero W.A.S.T.E.: Corralitos, CA | knowledge, reputations, information markets, Higher Power: 2^1398269 | black markets, collapse of governments. "National borders aren't even speed bumps on the information superhighway."

Tim replied:

Why not replace your entire architecture with reconfigurable hardware? Because factors of 2 or 3 or 4 or more are still important to people. Witness the clamor to upgrade from 166 MHz Pentia to 200 MHz MMX Pentia,etc. Now tell those folks that the FPGA version will cost several times as much and have the performance of a 90 MHz 486. Or less. All for what? So they can issue a "reconfigure yourself" command and have their machine spend a few minutes reprogramming itself into, what, a Mac?

A machine running on a reconfigurable FPGA will need an operating system that's not from Microsoft, so you get a factor of 4 or more back :-) But realistically, while FPGAs may be good for running special applications, you won't use it for random applications on different web pages; general-purpose processors get better and better at that. It might make an interesting peripheral, though, as DSPs once did. LISP machines were nice, but it was much easier to stay on the price-performance curve by tuning software better for general-purpose machines than by using elegant software on customized hardware; a 2:1 or 4:1 speed advantage is gone in 1-3 years, or faster if somebody improves the compiler, and there are lots more people improving compilers for mainstream machines than custom machines. Over the years there have been reconfigurable machines. VAXes used to have Writeable Control Store microcode; other than an occasional bux fix or update to the machine, the only people who used it were either very scary, very foolish, or had too much time on their hands, or else they were trying to do things that were way beyond the capabilities of the fine 1 MIPS machine they needed. (I used to play with virtual memory tunings, since it's hard to get a simulation algorithm that really needs 14MB of RAM to work well in a huge 4MB machine, and the normal virtual memory tunings got thrashed to death. WCS is worse...) # Thanks; Bill # Bill Stewart, +1-415-442-2215 stewarts@ix.netcom.com # You can get PGP outside the US at ftp.ox.ac.uk/pub/crypto/pgp # (If this is a mailing list or news, please Cc: me on replies. Thanks.)