850181f@aucs.uucp (S. Ferguson-Parker) (10/02/89)
I have a question to ask that may seem (be) stupid.
Is there *any* (speed etc.) difference between an old SE with the 800Kb
drives and the new SE with the 1.44Mb drives (outside of the space :-)?
The reason I ask is that Apple Canada is having a special event and they
list the price difference between these machines as almost $1000. An
interesting note is that the price of the external FDHD is $614. Does
that make any sence to anyone? Since I am about to buy one of these
things, a quick reply via e-mail would be appreciated.
Thanks
-----------------------------------------------------------------
Steven E. Ferguson-Parker Acadia Univ. School of Computer Science
Wolfville N.S. Canada BOP1XO
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BITNET: 850181f@Acadia
Internet: 850181f%Acadia.BITNET@CUNYVM.CUNY.EDU
Post: P.O. Box 846 Wolfville N.S. Canada B0P 1X0
-----------------------------------------------------------------c8s-an@franny.Berkeley.EDU (Alex Lau) (10/03/89)
In article <1989Oct2.050037.28499@aucs.uucp> 850181f@aucs.UUCP (S. Ferguson-Parker) writes: >Is there *any* (speed etc.) difference between an old SE with the 800Kb >drives and the new SE with the 1.44Mb drives (outside of the space :-)? The only difference is related to the drives. There is the new SWIM chip that the Superdrives need, and therefore System 6.0.3 is recommended due to fixes in the timing Manager or somesuch. > The reason I ask is that Apple Canada is having a special event and they >list the price difference between these machines as almost $1000. An >interesting note is that the price of the external FDHD is $614. Does >that make any sence to anyone? Since I am about to buy one of these >things, a quick reply via e-mail would be appreciated. The probable reason that Apple Canada is having the special deal is that they want to get rid of these 800K floppy-SEs. Nothing more, nothing less. By the way, the suggested retail for an external Superdrive is $629 in the U.S., and that comes with the measly warranty. >Steven E. Ferguson-Parker Acadia Univ. School of Computer Science --- Alex UUCP: {att,backbones}!ucbvax!franny!c8s-an INTERNET: c8s-an%franny.berkeley.edu@ucbvax.berkeley.edu FIDONET: Alex.Lau@bmug.fidonet.org (1:161/444)
gillies@m.cs.uiuc.edu (10/06/89)
Re: Expensive superdrives
How much difference is there between a superdrive and an IBM drive?
It's sad when a 1.44 3.5" IBM drive is $89 from CompuAdd, and
$350-$600 from Apple Computer, Inc.
Don Gillies, Dept. of Computer Science, University of Illinois
1304 W. Springfield, Urbana, Ill 61801
ARPA: gillies@cs.uiuc.edu UUCP: {uunet,harvard}!uiucdcs!gillieswilkins@jarthur.Claremont.EDU (Mark Wilkins) (10/07/89)
In article <8400174@m.cs.uiuc.edu> gillies@m.cs.uiuc.edu writes: > >Re: Expensive superdrives > >How much difference is there between a superdrive and an IBM drive? >It's sad when a 1.44 3.5" IBM drive is $89 from CompuAdd, and >$350-$600 from Apple Computer, Inc. Yeah, but the Apple drive reads both IBM and Apple disks.... since the two store information in fundamentally different ways, it was a difficult engineering task to create a drive which could read both. -- Mark Wilkins
klussier@rodan.acs.syr.edu (Kevin Lussier) (10/07/89)
I know that this has probably already been hashed around, but what exactly is the routine for upgrading from a regular 800k drive in the (only 1 year) older Mac SE to the new superdrive that comes with the news Macs? Kevin -- klussier@rodan.syr.edu | 'Look! Up in the sky. It's a bird, it's a plane, klussier@sunrise.syr.edu | it's Superman!'
allbery@NCoast.ORG (Brandon S. Allbery) (10/13/89)
As quoted from <8400174@m.cs.uiuc.edu> by gillies@m.cs.uiuc.edu: +--------------- | How much difference is there between a superdrive and an IBM drive? | It's sad when a 1.44 3.5" IBM drive is $89 from CompuAdd, and | $350-$600 from Apple Computer, Inc. +--------------- IBM-compatible drives use fixed speeds; Mac drives use variable speeds. The latter co$t$ more than the former, and supporting *both* co$t$ even more. (Why do Macs use variable speed drives? Because 400K floppies are that much nicer than 360K floppies (SS/DD), and 800K better than 720K (DS/DD). (Do SuperDrives provide a 1600K mode?) ++Brandon -- Brandon S. Allbery, moderator of comp.sources.misc allbery@NCoast.ORG uunet!hal.cwru.edu!ncoast!allbery ncoast!allbery@hal.cwru.edu bsa@telotech.uucp, 161-7070 BALLBERY (MCI), ALLBERY (Delphi), B.ALLBERY (GEnie) Is that enough addresses for you? no? then: allbery@uunet.UU.NET (c.s.misc)
jeh@elmgate.UUCP (Ed Hanway) (10/14/89)
In article <1989Oct12.231203.15676@NCoast.ORG> allbery@ncoast.ORG (Brandon S. Allbery) writes: >IBM-compatible drives use fixed speeds; Mac drives use variable speeds. >The latter co$t$ more than the former, and supporting *both* co$t$ even more. >(Why do Macs use variable speed drives? Because 400K floppies are that much >nicer than 360K floppies (SS/DD), and 800K better than 720K (DS/DD). (Do >SuperDrives provide a 1600K mode?) Not a very convincing argument since Commodore Amigas manage to get 880K on a normal, DSDD 3.5" floppy using a standard, fixed-speed drive. Macs are stuck with variable speed drives (or expensive, dual-mode ones) because they must maintain compatibility with old Mac "standards," not because there's any technical advantage to them.
gillies@m.cs.uiuc.edu (10/14/89)
I guess Macintosh drives also have servo-driven ejection. Apparently, PC drives do not eject by themselves.
tempest@wet.UUCP (Ken Lui) (10/15/89)
In article <1989Oct12.231203.15676@NCoast.ORG> allbery@ncoast.ORG (Brandon S. Allbery) writes: ... >(Why do Macs use variable speed drives? Because 400K floppies are that much >nicer than 360K floppies (SS/DD), and 800K better than 720K (DS/DD). (Do ... It's interesting that you brought this subject up because a friend of mine has an IBM PC, and is using a program that reformats DS/DD disks to 800K and (either 1.2Mb diskettes --> 1.44Mb or 1.44Mb diskettes --> 1.6Mb). So, it's possible to get the extra capacity with just fixed-speed drives. Given this situation, is there a program or is it possible to patch the MacOS to give us increased storage capacity? BTW, that program is only needed to format the diskette, and once formatted, any drive can read it. I always thought this variable drive speed was nice--400K on SS 3.5s and 800K on DS 3.5s--until I learned that the Amiga gets 880K on DS 3.5s. Ken -- _____________________________________________________________________________ Kenneth K.F. Lui | UUCP: ...{ucsfcca|claris}!wet!tempest tempest@wet.UUCP | Internet: cca.ucsf.edu!wet!tempest@cgl.ucsf.edu | -or- claris!wet!tempest@ames.arc.nasa.gov
rang@cs.wisc.edu (Anton Rang) (10/15/89)
[ Why do Macs have variable-speed drives? ]
The basic reason is because using a variable-speed drive was the most
reliable way of packing a lot of information onto a disk when the
drive was chosen.
With a fixed-speed drive, there are three approaches to putting lots
of data on a disk (well, besides single-sided vs. double-sided):
(1) Using a more compact encoding scheme. This is how Apple ][s
went from 13-sector to 16-sector drives. The hardware for this
can get expensive, though, and current systems come pretty close
to "perfect" as far as this goes (at least, without $$$ decoding
hardware).
(2) Putting more sectors on a track--driving the read/write head
faster. This physically packs data closer together, at the
cost of needing a faster R/W head setup. Also, some magnetic
media which can support a high density is needed.
(3) Putting more tracks on the disk--putting them closer together.
This requires more accuracy in positioning the head, a "smaller"
head, and high-density media.
Options (2) and (3) require high-density media with very high quality-
control standards, because the bits are actually closer together.
Using a variable-speed drive mechanism means that you can put more
sectors on outer tracks, without packing data closer together on the
inner tracks. In general, as long as the speed control works, this
will be more reliable than (2) or (3) because a larger area of the
disk is magnetized for each disk.
(Does anyone have wear figures for 800K disks vs. HD disks? I
looked through some back ASLE issues but couldn't find any...)
+----------------------------------+------------------+
| Anton Rang (grad student) | rang@cs.wisc.edu |
| University of Wisconsin--Madison | |
+----------------------------------+------------------+marc@Apple.COM (Mark Dawson) (10/16/89)
In article <670@wet.UUCP> tempest@wet.UUCP (Ken Lui) writes: >In article <1989Oct12.231203.15676@NCoast.ORG> allbery@ncoast.ORG (Brandon S. Allbery) writes: >... >>(Why do Macs use variable speed drives? Because 400K floppies are that much >>nicer than 360K floppies (SS/DD), and 800K better than 720K (DS/DD). (Do >... > >It's interesting that you brought this subject up because a >friend of mine has an IBM PC, and is using a program that >reformats DS/DD disks to 800K and (either 1.2Mb diskettes --> 1.44Mb >or 1.44Mb diskettes --> 1.6Mb). So, it's possible to get the >extra capacity with just fixed-speed drives. Given this >situation, is there a program or is it possible to patch the >MacOS to give us increased storage capacity? > >BTW, that program is only needed to format the diskette, and once >formatted, any drive can read it. I always thought this variable >drive speed was nice--400K on SS 3.5s and 800K on DS 3.5s--until >I learned that the Amiga gets 880K on DS 3.5s. > I believe its a function of the disk controller chip. Kennect's Rapport device can get 1.2mb on DSDD 3.5" disks using a section of Apple's SWIM chip. Apple's old IWM disk controller chip just couldn't handle it. If you don't have a variable speed drive, to get some of the high densities (like the 1.2mb format), you need to be able to vary the data rate on the disk controller chip. I believe the IWM doesn't support variable data rates, while the SWIM does. Mark
oplinger@minerva.crd.ge.com (B. S. Oplinger) (10/17/89)
In article <1989Oct12.231203.15676@NCoast.ORG> allbery@ncoast.ORG (Brandon S. Allbery) writes: >As quoted from <8400174@m.cs.uiuc.edu> by gillies@m.cs.uiuc.edu: >+--------------- >| How much difference is there between a superdrive and an IBM drive? >| It's sad when a 1.44 3.5" IBM drive is $89 from CompuAdd, and >| $350-$600 from Apple Computer, Inc. >+--------------- > >IBM-compatible drives use fixed speeds; Mac drives use variable speeds. >The latter co$t$ more than the former, and supporting *both* co$t$ even more. >(Why do Macs use variable speed drives? Because 400K floppies are that much >nicer than 360K floppies (SS/DD), and 800K better than 720K (DS/DD). (Do >SuperDrives provide a 1600K mode?) Well, I'm definately sure that it is not density, as any Amiga or Atari ST owner can tell you (they both use MFM 400/800K floppies). I heard it was that the original design people at Apple didn't understand the concept of fixed angular velocity and chose a design which produced (somewhat) fixed linear speed. That is, for each speed band the edges are within +/- n of the center band speed ( which is the same for all center tracks ). Anyone from Apple care to comment? brian oplinger@crd.ge.com < #include.disclaimer >
bergman@m2c.m2c.org (Michael Bergman) (10/18/89)
This thread should probably be renamed "variable speed drives", but I'm not going to do it...I spoke to someone from Kennect about how their drive works, and he said that by using BOTH apples variable speed drive AND IBM's formatting method, they get their 2.4 Meg micro-floppies (which no one else can read) -- so the answer to the question seems to be "you're both right" -- there is no great advantage to using variable speed drives over fixed speed drives, its just that the variable speed drives came first, but there is an advantage to mixing the two technologies. (I had asked the engineer at Kennect how they got 2.4 Meg onto an HD disk without exceeding the rated capacity of the disk) -- --mike bergman Massachusetts Microelectronics Center 75 North Drive, Westborough, MA 01581, USA +1 (508) 870-0312 UUCP: harvard!m2c!bergman INTERNET: bergman@m2c.org
allbery@NCoast.ORG (Brandon S. Allbery) (10/20/89)
As quoted from <670@wet.UUCP> by tempest@wet.UUCP (Ken Lui): +--------------- | In article <1989Oct12.231203.15676@NCoast.ORG> allbery@ncoast.ORG (Brandon S. Allbery) writes: | ... | >(Why do Macs use variable speed drives? Because 400K floppies are that much | >nicer than 360K floppies (SS/DD), and 800K better than 720K (DS/DD). (Do | ... | | It's interesting that you brought this subject up because a | friend of mine has an IBM PC, and is using a program that | reformats DS/DD disks to 800K and (either 1.2Mb diskettes --> 1.44Mb | or 1.44Mb diskettes --> 1.6Mb). So, it's possible to get the | extra capacity with just fixed-speed drives. Given this | situation, is there a program or is it possible to patch the | MacOS to give us increased storage capacity? +--------------- I doubt it, since it's probably a limitation of the IWM. The new SWIM chip in the FDHD-equipped Macs might be able to handle it. PCs get 400K/800K/etc. by increasing the number of sectors per track from 9 to 10. The Mac, if I recall, uses variable sectors per track as a result of its speed diddling. This is the reason why most other machines don't understand Mac disks. +--------------- | BTW, that program is only needed to format the diskette, and once | formatted, any drive can read it. I always thought this variable | drive speed was nice--400K on SS 3.5s and 800K on DS 3.5s--until | I learned that the Amiga gets 880K on DS 3.5s. +--------------- Chances are the Amiga pushes the limits on the disk's capabilities: for example, on many PClones you can get 42 tracks of 10 sectors (420K) on a nominal 360K disk. ++Brandon -- Brandon S. Allbery, moderator of comp.sources.misc allbery@NCoast.ORG uunet!hal.cwru.edu!ncoast!allbery ncoast!allbery@hal.cwru.edu bsa@telotech.uucp 161-7070 (MCI), ALLBERY (Delphi), B.ALLBERY (GEnie), comp-sources-misc@backbone [comp.sources.misc-related mail should go ONLY to comp-sources-misc@<backbone>] *Third party vote-collection service: send mail to allbery@uunet.uu.net (ONLY)*
jca@pnet01.cts.com (John C. Archambeau) (10/20/89)
tempest@wet.UUCP (Ken Lui) writes: >It's interesting that you brought this subject up because a >friend of mine has an IBM PC, and is using a program that >reformats DS/DD disks to 800K and (either 1.2Mb diskettes --> 1.44Mb >or 1.44Mb diskettes --> 1.6Mb). So, it's possible to get the >extra capacity with just fixed-speed drives. Given this >situation, is there a program or is it possible to patch the >MacOS to give us increased storage capacity? I'm very familiar with this IBM compatable utilities to get extra capacity out of certain floppies (720K DS/DD 3.5", et. al.). What these programs do is simple. They add an extra track to the disk. It is NOT recommended that these utilities be used since they use 'questionable' areas of the disk to plop down that extra track. It might work from your experience, but I won't use it because there's no guarrantee that it will work 100% of the time. Will it work under VP/ix (aka DOSMerge or a DOS window) under a *nix based OS? Probably not. I'm not willing to make such a gamble with my data since I do read DOS file systems on *nix based OS'es via VP/ix. I know that they have problems formatting. At least the Sun 386i/250 at work refuses to format my 3.5" disks that will format perfectly on my AT (and conversely read and write perfectly on the 386i) at home. /*--------------------------------------------------------------------------* * Flames: /dev/null (on my Minix partition) *--------------------------------------------------------------------------* * ARPA : crash!pnet01!jca@nosc.mil * INET : jca@pnet01.cts.com * UUCP : {nosc ucsd hplabs!hd-sdd}!crash!pnet01!jca *--------------------------------------------------------------------------* * Note : My opinions are that...mine. My boss doesn't pay me enough to * speak in the best interests of the company (yet). *--------------------------------------------------------------------------*/