FPGA VAX update

Chuck> On 11/3/2005 at 9:49 AM Paul Koning wrote: Chuck> ...or one could use a MIPS chip... Chuck> To me, the genius (and unrecognized at the time) of the 6600 Chuck> architecture was Cray's discarding the idea of a "condition Chuck> code" in the IBM sense, wherein the state of a result is Chuck> actually divorced from the result itself. That's useful indeed, though there were plenty of other machines back then where this was true. I believe the more significant innovations were the extensive parallelism and the quantity of registers. Chuck> But I don't have rose-colored glasses either. The "call" Chuck> (return jump) instruction implementation was an abomination Chuck> because it actually stored the return address as a jump Chuck> instruction in program memory, rather than putting it in a Chuck> register. ... True. Again, something that was conventional back then. Chuck> I still wonder about Chuck> the utilitiy of the "count the 1's" instruction. The rumor has it that the NSA asked for it. Certainly that makes sense. It was also used extensively in the PLATO system. If you want to do fuzzy matches (i.e., accept misspellings for words), a nice way to do that is to encode the words in a clever way, XOR the intended word with the supplied one, bitcount the difference, and accept it if the number of bits that differ is less than N. Chuck> I know this seems ridiculous with today's fast CPUs and the Chuck> amount of bloatware around, but getting tight code was a mark Chuck> of pride back in those days. Sure was. 600 timesharing terminals on a pair of 10 MHz processors is pretty slick. (Come to think of it, over 9000 timesharing terminals on a single Alpha-based descendant of that system is mighty impressive, too.) paul