[PLUG-TALK] Oversize 2.5" Hard Drive

alan alan at clueserver.org
Fri Jul 20 14:47:41 PDT 2007

On Fri, 20 Jul 2007, Keith Lofstrom wrote:

> On Thu, Jul 19, 2007 at 03:24:48PM -0700, Rich Shepard wrote:
>>   I replaced the IBM Travelstore 10G, 5400RPM hard drive in the ThinkPad
>> 600E with a Hitachi 80G, 7400RPM drive. When I tried to put the IBM drive in
>> an enclosure sold for 2.5" IDE hard drives, it would not fit: too wide. It
>> measures closer to 2.75" wide. Is this a fairly common situation? Are there
>> enclosure brands that are larger than others?
>>   I'm not looking forward to driving all the way back to Fry's to return the
>> enclosure unless I know that there are ones made into which this wider drive
>> will fit.
> 0) All drives are about 2.75 inches wide ( and 1 GB = 0.93 GiB, so they
> exaggerate sizes in both directions, lying dogs!).  Some older ones are
> too thick, but the 10GB Travelstars I've seen are all about 10mm .  Most
> IBM laptops put the drives in "caddies", thin metal shells with 2 screws
> on each side that adapt the drive to the laptop.  A drive with the caddy
> surrounding it will not fit some external enclosures.

Actually the sizes are 12mm, 9.5mm and 6.35mm.  The 6.35 was made only by 
Toshiba for the Toshiba Libretto, but also used in some of the tiny laptop 
systems.  I don't know if they still make them in that form factor.

The 12mm drives are also pretty rare.  You only saw them on real old 

I might still have one or two of the older drives.  Nothing bigger than 
about 10gigs though.

As for size of drives:

The marketing people found that if they called 1 meg == 1000000 bytes, 
instead of 1048576, they sould make it look bigger.  (They probably also 
measure themselves with a metric ruler.)

1 meg != 1000000 == 1048576
1 gig != 1000000000 == 1073741824

Clearly a ripoff, but they have gotten away with it for over 20 years, so 
it will probably never change.

Bill Hicks was right about Sales and Marketing.

"ANSI C says access to the padding fields of a struct is undefined.
ANSI C also says that struct assignment is a memcpy. Therefore struct
assignment in ANSI C is a violation of ANSI C..."
                                   - Alan Cox

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