Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!cbosgd!ihnp4!houxm!whuxl!whuxlm!akgua!gatech!seismo!hao!hplabs!tektronix!reed!bart From: bart@reed.UUCP Newsgroups: net.micro.mac Subject: (LONG FLAME) Re: Don't rag on the IWM Message-ID: <2600@reed.UUCP> Date: Tue, 25-Feb-86 04:16:25 EST Article-I.D.: reed.2600 Posted: Tue Feb 25 04:16:25 1986 Date-Received: Fri, 28-Feb-86 23:03:28 EST References: <635@well.UUCP> <2497@reed.UUCP> <9607@amdcad.UUCP> <2572@reed.UUCP> <113@Shasta.ARPA> Distribution: net Organization: Reed College, Portland, Oregon Lines: 126 I'm afraid I couldn't resist responding to a reply to my reply to someone's article. But this is my last word on the subject. Honest. I just couldn't take the article this references. So, Holy Cleansing FLAME ON... In article <113@Shasta.ARPA> Gus Fernandez says: > The problems you are having are strictly mechanical hardware related. If this were true, so what. It would just support my original contention that the 3.5" Sonys are fairly ugly drives... > The IWM puts out just as reliable a > disk format as anything that an IBM machine spits out. In some ways, it's more reliable. There are the tag bytes, for instance. But it's *group encoded, not MFM* . Do a worst case comparison of the two systems, and think about it, before you make these claims. MFM simply stores more redundant information per bit (namely 1 bit's worth, more or less). This doesn't help in error *correction*, but it does help in error *detection*, because when the PLL in an MFM chip gets off, it KNOWS it's because of a bad bit. > The IWM is also no slower than other disk formats. This is even more untrue. It is true that even if the Mac used IBM style drives and controllers, it would be much slower than the PC (for floppy io). But the IWM is *driven from software*. The disk drivers have to do serial port polling to avoid dropping characters, for pete's sake! Thus, while the machine is reading a sector, it spends most of its time staring at the IWM. This makes it intrinsically slower than a typical disk controller chip, which receives a "read sector" instruction and then transfers the sector at the maximum floppy bandwidth using DMA. > The reason that Mac disk access seems slow > is that the Mac uses a much more sophisticated two-layer file architecture > that IBM. By two layers, I mean first the file system layer, and then the > resource layer. Generally such systems are slow at first in that common > inter-layer interactions are not optimized. The new ROM's solve this problem > in at least FOUR ways; > 1: Track cache Nice. But ultimately, one is still limited by drive speed. I presume the new cache is write-through, for instance (please?!?)... > 2: File cache Existed already. Hopefully bigger and better, though... > 3: Resource manager optimizations > 4: Supercharged resources. But note that all 4 of these things are independent of the choice of floppy and controller. Think how nice they'd be on a faster floppy! > I am not even counting HFS and 800K drives. Good plan. Not only do neither of these things have anything to do with the choice of drive and controller, but HFS is *slower* in many cases because it has to work harder, and the 800K drives are the same technology as before, + or - some small speed increase from reading two sectors at a time (if the IWM can do this, BTW. Can it?). > The problem with error reporting > is indeed a sticky one. Should a floppy based OS display an MS DOS read error > message a la MS DOS, or should it handle errors internally? There are > arguments both ways. One argument says that in the case of a read error, the > user should be informed that something is wrong. On the other hand, by then > it may be too late anyway. I guess my philosophy is if it's gonna try to handle errors internally, the machine #$%^ well better *handle* them, and keep them from hurting anything. If it can't, I'd ^&*@ well like to know what went wrong so I can take steps to correct it myself... > Case and point. I bought a copy of EASY3d last > month. The supplied disk had a manufacturing flaw (a read error on one of the > sectors.) The program worked fine but I kept on hearing the disk recalibrate > every time I launched the program. The program could also not be copied even > though the label said that it was not copy protected. I want in with the > resource manager and a sector editor and found that indeed there was a bad > block, but I was able to recovering using bit-level microsurgery. The result, > a new menu item appeared on the screen that was not there before. Now try > THAT with an IBM! Not any harder on the IBM than the Mac. In fact, easier. With the IBM, one generally just reads the bad sector for starters, then writes it back with the correct checksum. This makes it readable. Then one tries to figure out which byte in the sector is bad, which is normally no harder than on a mac... Even more to the point, wouldn't it have been nice if there had been some indication of a disk problem other than the sound the drives made? I'm afraid I don't have your ear... > > At any rate, 50% PC floppy drive failure > > rates are unusual, in my experience. > > Besides, many PCs contain third party floppy drives. Try that on a Mac! > > Several third pary floppy drives ARE available for the Mac. The habba drive > and the maple drive are two examples. What I meant to say was that many PCs are *sold* with third party drives. This is what I meant by "contain". Sorry I was unclear. > > Admittedly, not all Mac drives are bad. But the percentage rate, here, > > is high enough to make me angry. Especially when my machine at home is > > one of them. > Nobody should jump to conclusions with a limited sample, even if it's their > own. The aggravated shout the loudest. The vast majority are silent. For pete's sake, at least *read what I wrote*. When I say "the percentage rate here" I mean AT REED COLLEGE. We have MORE THAN 200 MACS here. MANY of them have drive problems. Yes, I'm shouting because I'm aggravated! And I'm aggravated because I'm tired of seeing Mac floppy problems all over campus! And the "vast majority" sure as $%^& hasn't been silent on this general topic. Read back over net.micro.mac . ...FLAME OFF I repeat: I do not think the Mac is evil. I like it very, very much. And I do not think the IBM PC is wonderful. I dislike it more than a little. I do not even think the floppy or controller makes the Mac unusable. I just think Apple could have chosen better ones. Still. Disked Out at Reed College, -- Bart Massey ..tektronix!reed!bart