Post #74,829
1/16/03 6:40:57 AM
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Remember that well
We had a software contract with IBM at the time. We ran through 3 disks in 2 months - they had a design flaw in the head positioning mecahnism - magnetic material would be knocked off the platter by the head and accumulate on the head motion bar, occluding the optical registration marks and making it impossible to locate the head at the correct cylinder.
I hardly count that against IBM. Who else was offering machines with hard disks at that time? Don't think the original Mac had one..
(BTW I thought it was Seagate - almost knocked them out of business.)
-drl
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Post #74,886
1/16/03 11:08:40 AM
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For the record.
The original Mac (Mac Classic) ran off of a floppy drive + 128mb RAM.
Barely.
Any deity worthy of a graven image can cobble up a working universe complete with fake fossils in under a week - hey, if you're not omnipotent, there's no real point in being a god. But to start with a big ball of elementary particles and end up with the duckbill platypus without constant twiddling requires a degree of subtlety and the ability to Think Things Through: exactly the qualities I'm looking for when I'm shopping for a Supreme Being.
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Post #74,905
1/16/03 12:49:06 PM
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The First Mac
ran off of a 800K Floppy Disk and 128 Kilobytes of RAM, no hard drive, not even a SCSI (Not until the Mac Plus, IIRC). I am sure you meant to put in there 128 kb instead of mb. 128 mbs was more than hard drives of the day could store on them. :)
The "Fat Mac" or Mac512K offered 512 kb of RAM, then the Mac Plus came along and changed everything with SCSI ports, 1 mb of RAM, etc.
Later in 1987, the Mac SE came out (I own one) and had an internal expansion port, something the Mac really needed to be taken seriously in the corp environment. How else could they drop in a Network card? Something that Apple didn't copy from Xerox, was the built in networking, at least not until later.
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Post #74,889
1/16/03 11:18:45 AM
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Slim pickings on CMI drive, but here's some:
IBM\ufffds original hard drive for the AT had a 40-millisecond average seek time and held 20 megabytes. That drive, built for IBM by a company called CMI, was unreliable. IBM eventually switched to a different supplier, and CMI went bankrupt.
Most clones contain reliable drives that go faster (28 milliseconds) and hold more (40 megabytes and beyond). [link|http://www.gis.net/~poo/27ibm.html|Link] for the above. Also, [link|http://www.rdrop.com/~jimw/j-hist.shtml|CMI Model 6426-S Hard Disk Drive]. This is the item that almost single-handedly ruined IBM early in the Personal Computer age.
CMI was the only company at the time that could produce a drive that would meet the then almost unimaginable specifications for seek time that IBM had required for a hard drive for their new (at the time) IBM 'AT' computer.
The drive was fast alright, but had a hidden flaw... The drive gained its speed by using a rotary actuator to move the heads rather than the more traditional stepper motor. This required that a 'servo' track be written on one of the disk platters to provide the information that the drive logic used to center the heads on the selected track.
What quickly became apparent soon after the computer went in to production, was that the drives had a operational life of about three months! A flaw in the drive circuitry gradually erased the servo track, causing the drive to be unable to position the heads accurately which either began to corrupt data, or one day the drive would just refuse to function.
Frantic (and very expensive) efforts were made to do 'damage control' on the situation, and IBM replaced thousands of these drives only to see the replacements start to fail as well. This whole fiasco severly damaged the reputation of both IBM and the 'AT' computer, and it was some time before either fully recovered.
Nearly all of the CMI drives were eventually recalled and replaced, (with drives from a different manufacturer and somewhat relaxed specifications) and the entire lot of drives were eventually thrown on a barge and dumped in the ocean off of the Florida coast in order to create a foundation for a new submerged reef. To their credit, IBM did try to fix the problem. Alex
"No man's life, liberty, or property are safe while the legislature is in session."\t-- Mark Twain
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Post #74,945
1/16/03 5:17:33 PM
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Re: Slim pickings on CMI drive, but here's some:
Wow, that's new to me. This is a completely different issue than the one with the Seagate drives. In fact I'm sure I've never heard of CMI (not the same as CMS, a third party supplier of PS/2 SCSI hardware).
Our ATs were delivered in early 1985 - when did the very first IBM AT ship?
We used our AT as a network server way back then - a real, original IBM NETBIOS network.
-drl
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Post #75,004
1/16/03 9:52:06 PM
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First ATs were shipped in 1984. So you may...
have been lucky. Working for IBM, I had a pre-release version w/CMI drive.
Alex
"No man's life, liberty, or property are safe while the legislature is in session."\t-- Mark Twain
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Post #75,017
1/16/03 11:08:45 PM
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You could hear..
..the gentle whirring of the stepper motor as it moved the head around. It was certainly a Seagate drive.
Funny, I can almost imagine the layout of the AT mobo, not having seen it in 17 years.
-drl
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