What is the difference between flashdisk memory and normal hard disk memory?

Answer 1

Flashdisk memory is usually some sort of solid-state memory that can be read over a memory bus via random addressing. No head-seek time. No rotational delays. The only limit is the speed of the connection - firewire or USB or whatever - and the speed of the addressing circuitry.

Hard drives rotate and move heads. A head move takes milliseconds - 5 to 10 msec depending on the age of the drive and its size. 8 msec is not uncommon. Below 5 msec is tougher to find but is out there.

You also have to wait for the selected sector to pass under the heads AFTER those heads are on the right track because the disk rotational speed is constant. Rotational latency depends on the rotation rate of the drive. For a 7200 rpm drive, you have 120 rps or one rotation every 8.333... milliseconds.

If you add those up and have the worst case possible, you might have to wait 15-16 msec for the data you want from your hard drive. In effect, you would be limited to 60 disk ops per second if that was your average op timing.

Why is that so bad? These days, computers execute their instructions at rates in excess of 2 GigaHertz. A 2 GHz machine executes its instructions at roughly 500 MHz to 1 GHz (depends on the number of machine cycles for a given instruction.) Well, at that rate, 10 msec = 5 million to 10 million instructions. That should put it in perspective for you.

Answer 2

flash disk is like a flashdrive protable while hard disk is built in

Answer 3

Their really isn't any difference besides the size of the space.

Answer 4

hard disks rotate and flash are solid state (dont rotate)

Answer 5

flashsticks can be carried in your pocket hardrives cannot.