Weekly Classic Computer Trivia Question (20141205)

Peter Corlett abuse at cabal.org.uk
Sat Dec 6 08:02:52 CST 2014

On Fri, Dec 05, 2014 at 11:35:54PM -0500, Mouse wrote:
> "The standard"?  That disagrees with my experience.  I have numerous disks
> from the days when capacities were several tens of megabytes, or low hundreds
> of megabytes; they are all labeled accurately.

My ratty old tiny disks are all in storage so I can't pull a few out and check
the CHS/LBA versus the marked capacity, but I note that When it comes to mere
megabytes, 1000**2 and 1024**2 are still close enough for it to be lost in
rounding errors.

> Somewhere around the time of single-digit gigabyte capacities, disk
> manufacturers started mislabeling their disks.  That they were doing so
> knowing it was an actively misleading practice is evidenced by the notes in
> ads from that era (and even on some drives), saying things like "based on 1GB
> = 1 billion bytes", which, if the metric meanings were indeed the standard
> you seem to be claiming they were, would not have been worth mentioning.

Actually, the notes in the ads were added later due to litigious bastards and
other chancers claiming that they believed it to mean powers-of-two and making
a nuisance of themselves in court.

This power-of-two confusion is an artifact of how solid-state memory devices
are made, and does not apply to everything vaguely related to computers.
Otherwise one could try and argue that a "dozen eggs" should contain 13 eggs
because bakers add an extra loaf to a batch as an artifact of the bread-making

Consider also the infamous 1.44MB disk.  That number comes from 1440 * 1024, so
apparently a megabyte is *also* 1,024,000 bytes.  If we can humpty-dumpty it
and pluck numbers out of the air, why not just call a megabyte 3,141,592 bytes?

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