Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/12/84; site desint.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!ihnp4!houxm!whuxl!whuxlm!akgua!sdcsvax!sdcrdcf!trwrb!desint!geoff From: geoff@desint.UUCP (Geoff Kuenning) Newsgroups: net.micro.16k Subject: Re: Corrigenda (24-bit addresses) Message-ID: <351@desint.UUCP> Date: Fri, 8-Mar-85 18:05:50 EST Article-I.D.: desint.351 Posted: Fri Mar 8 18:05:50 1985 Date-Received: Mon, 11-Mar-85 11:26:51 EST References: <794@sjuvax.UUCP> <5025@utzoo.UUCP> <2342@nsc.UUCP> Organization: his home computer, Manhattan Beach, CA Lines: 50 In article <400@terak.UUCP> doug@terak.UUCP (Doug Pardee) writes: >> (a) 32 bits is a bit less than five Eagles worth of byte-addressed data. I >> can easily concoct a microprocessor application where direct addressing >> of that data space is desirable, if not necessary. > >A *microprocessor* application???? Come on now, let's get serious. >I _might_ grant that for an AI application you would need that kind >of high-speed random-access memory, but no sane person would *ever* >choose a 68xxx/32xxx type processor for AI. You need a *lot* more >MIPS than that. > >Let's see, using 256K DRAMs at $15 each, the cost of the RAM chips >alone... [there follows a complicated analysis of costs that concludes one would have to expend $20 billion on RAM chips to get 4 Gbytes] >So you're gonna spend maybe 20 G's or more on a memory system, and >to "cut costs" you're gonna use an off-the-shelf microprocessor like >a 68020 or 32032? Gimme a break! Give me a break yourself. The part you quoted *explicitly* mentions the Fujitsu Eagle, which is a disk drive. Like I said before, I can easily concoct a MICROPROCESSOR application that needs to address 32 bits worth of MASS-STORAGE-RESIDENT data. Surprise, surprise, it isn't going to be a CPU-bound application. It's going to be some sort of database-intensive application. It is true that there are other ways to handle disk-resident databases (or other media; trillion-bit memories on obscure slow media date back to the late 60's) than as virtual memories. Having done so, I can testify that you will *always* wind up writing code that, in effect, simulates the virtual memory hardware in software. Sometimes you are lucky and you can hide it pretty well. But sometimes you have truly random reference patterns that really do exhibit locality in short time spans, and then you have to do it in software. I know; I've done it in software myself on more than one occasion. No thanks. I might add that, even in a system that does not have virtual memory, a wide address/data path makes writing software-virtual code much easier. National got this part right, at least. The funny thing is that you hear pretty much the same noises from Intel as from National -- just replace all occurrences of "24" by "16". -- Geoff Kuenning Unix Consultant (213) 545-4413 ...!ihnp4!trwrb!desint!geoff