Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!apple!oliveb!pyramid!ncc!myrias!alberta!cdshaw From: cdshaw@alberta.UUCP (Chris Shaw) Newsgroups: comp.arch Subject: Re: In defense of the VAX Message-ID: <2066@pembina.UUCP> Date: 22 Feb 89 08:45:09 GMT References: <4592@tekgvs.LABS.TEK.COM> <638@m3.mfci.UUCP> <11037@tekecs.TEK.COM> <653@m3.mfci.UUCP> Reply-To: cdshaw@pembina.UUCP (Chris Shaw) Organization: U. of Alberta, Edmonton, Alberta, Canada Lines: 66 In article <653@m3.mfci.UUCP> rodman@mfci.UUCP (Paul Rodman) writes: >>Paul Rodman at Multiflow (rodman@mfci.UUCP) writes: >> >> "Personally, I think the vax has about the worst possible >> archtecture one could come up with ... > >Look, you don't think there weren't any parts in the model T that >could've been done better? This is trivially true. Times change. Ivan Sutherland once made a salient point: "Perfection is the enemy of the dissertation" In other words, the task is to come up with something good in a reasonable amount of time, not something perfect. Realize also that the context of VAX design was 1975, not 1989. Memories being sold then were 4116's (or smaller, I don't know, I was 12 at the time). Consider: 16K DRAMs versus 4Meg (or 8 or 16). You can't design an architecture based on the next decade's memories unless you're prepared to wait for them. It doesn't matter whether you can see the trend or not, what matters is whether you can sell machines today given today's raw materials. >An interesting thought experiment would be to take the same group of people, >get them in a room and say "If you were transported back in time and could >know what you know now, what kind of machine would you build?". Interesting, but not very intellectually satisfying. Of course they'd design something different. That's not the point. The interesting question is whether the people setting the business constraints circa 1975 would be willing to trade 1978-1983's sales for 1984-1989's sales, given that 1989 knowledge will result in a machine that might not sell if implemented in 1975 technology. I guess the point that Klossner was trying to make was as follows: It's obvious that by today's standards, the VAX sucks. So by saying that the VAX sucks, Paul Rodman must clearly mean something else, and the only conclusion one can draw is that Paul Rodman thinks the VAX designers were stupid. Well, Paul Rodman doesn't think that the VAX designers were stupid, he just says the VAX is stupid. However, it's a grave mistake to judge the "inner quality" of yesterday's engineering by today's standards, especially in a field that moves as fast as this one. All you can do is learn from its mistakes given the updated context. The biggest challenge with this field compared to other engineering is that requirements change, and a large part of the engineering process is looking into the crystal ball to see what's next. Compared to the Model T example, you don't suddenly find the the average Model T owner wants to haul 150 people per trip. It's easy to understand what the fundamental limitation is for cars. For computers, the fundamental limitation moves very quickly. Todays excellent engineering is tomorrow's foolish mistake. Because of the high speed of improvement in electronics, I think it's inevitable that a ten year old machine will look hideously out of date. Ten year old computer fashions look as silly as ten year old clothing fashions, and for a similar reason: today's constraint of technology or taste is not the same as tomorrow's. One doesn't fine tune a design too much because the time is better spent building the next iteration. > Paul Rodman > rodman@mfci.uucp -- Chris Shaw cdshaw@alberta.UUCP (or via watmath or ubc-vision) University of Alberta CatchPhrase: Bogus as HELL !