On 1/7/25 17:00, Charles Curley wrote:
On Tue, 07 Jan 2025 11:09:06 -0800
Kushal Kumaran <kus...@locationd.net> wrote:
I point people to http://www.tarsnap.com/GB-why.html which is where I
was first enlightened.
Mr. Tarsnap forgets something. The reason disks are addressed in powers
of two has to do with mathematics. Every hard and floppy disk out there
has flaws. To get around that, data is divided into sectors, and
checksums calculated. Done right, this allows for error correction for
small flaws. The math works out better if you do it in chunks that are
integer powers of two. So floppy disks have sectors of 256 octets, and
their attendant checksums. Modern hard drives schlep data in chunks of
4096 (2^12) octets. And bytes these days are eight bits.
This business of using powers of ten to describe hard drives came from
hard drive marketing weanies. They realized that using powers of ten
made their drives *look* larger to the uninitiated. I worked at Maxtor
about the time this was happening, and that's what the marketing
weanies told me.
The marketing weanies used GB for the powers of two numbers and for the
powers of ten numbers, which, it it wasn't fraud, skated damned close.
Someone since then has come up with GiB, making it possible to
distinguish between the two.
I don't much care. Americans use both imperial measures (miles) and
metric (35 mm film, liter bottles of pop). The agile ones can use both.
Mass is mass, whether you measure it in grams or pounds, on the Earth
or on Luna. My lathe (Hi, Gene) is calibrated in millimeters: one turn
of the handle moves the table 1 mm, and it is graduated in increments
of .05 mm. I have both inch and metric taps, dies and drill bits. And
lettered drill bits. GB or GiB? I don't care, just be clear which one
you are using.
My basic unit on the lathe is .0002" for calibration purposes. Is the
finest resolution for the encoder dials that serve as the xz cranks that
is one click of a 100ppr encoder when g20 is in default mode. Entering
g21 instantly converts everything to metric for display. But that would
be quite slow in either mode, so those dials have pushbuttons that
switches the span of a click on a 2,5,10,20,50 etc basis. Driven by
holding the button down and turning the dial. I can jog it to a new
position at speeds up to 260 ipm, then do a touch off at an .001mm or
.0002" accuracy. That beats what you can do with the conventional
mechanical cranks. Not by much but it is important for shrink fitting
stuff.
FWIW, my 3d printer rebuilds are all metric screws, usually self tapping
as I print 90% of the new parts.
Thus ends the rant.
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
