micky said:
OT can dropping something destory just a bit of its memory?
I guess I know the answer, but I want to hear anything you all know
about this. Six months ago, I dropped my smart phone on a ceramic
tile floor, and when I turned it on right after that, the start-up
images -- I forget what they had been on an AT&T phone -- had changed
to 3 rectangles, of different shapes and different colors, each a
solid color. It continues to work like that. But afaict,
everything else about the phone works as it used to.
Have you ever heard of something like this before? Comments?
I ask because of curiosity and, in part, because my brother is
absent-minded enough that he might have put his laptop in a suitcase
and checked it when he flew and the baggage-men might have thrown it
around. Maybe that is why the OS now can't find his profile.
Even though the profile is stored on the harddrive and the graphics
for my phone are -- afaik -- stored in ROM or RAM inside the phone.
Thanks.
Flash memory is quite resistant to reasonable levels of shock.
Maybe up to 1000G deceleration (striking a solid metal plate).
The plastic housing of a lot of modern electronic devices, has
enough spring force, to prevent such a high G deceleration force
to be achieved. The high G forces might crack the PCB and break
a connection to the chip, as an example of a failure mode.
Disconnection of a pin, could prevent the device from operating.
What could have happened to the phone, is a brief power interruption
that corrupted some portion of its file system. Rather than
"individual bits popping out and hitting the floor". That doesn't
happen. But maybe some file system writes were in progress, and
there was some damage to the file system. The springs on the
battery pack, could open and close electrical contact rapidly.
*******
To protect a computer in transit, you need the same kind of protection
ideas. No "solid to solid" contact, which could achieve a high G force.
It's not necessarily the amount of padding, as it is the
complete job you do. Like, protecting sharp corners on purely
rectangular objects. If an object pokes through the box, and then
that rectangle makes contact with a concrete floor in the shipping
area, that can be enough to exceed the G force limit for a parked
hard drive.
Some hard drives, the head assembly slides up a landing ramp. There
is a detent and a place for the heads to rest. That prevents the
heads from clattering against the platter. And is one of the reasons
amongst others, that a powered off hard drive has a better shock
rating, than when the platter is spinning and the heads are floating
over it. (On my current hard drive, the operating G limit is 30G,
and the parked G rating is 300G. On much older drives, the
operating G limit was only 2Gs, and you couldn't "jump on the
floors" with those running.)
The 300G number, to put this in perspective, it's a matter of
how much intervening materials have a springy response to
compression, that helps determine the G level achieved. If
you drop a steel ball bearing onto a thick steel plate, that
can be over 1000G of deceleration when the steel objects hit.
(We measured that in Physics 100 class in university.)
Things that compress a bit (plastic housings), prevent
those kinds of levels from happening. So even the laptop housing
itself, might prevent getting to 300G level. You're as likely to
have the laptop frame deflect, the casing gets torqued, the
twisting action snaps the LCD screen, the twisting action
snaps the hard drive SATA connector, and so on. And laptop
designs do take twist and torque into account when they design
them, so they do try to prevent stuff snapping in normal usage.
The engineers know the framework is not a solid, and is flexible
enough to cause problems. But you can't make current LCD
screens completely bulletproof to that sort of thing,
so they can still crack. That's if the twisting is bad enough.
Paul
