Consider a disk with the following characteristics (these are not parameters of any particular disk unit): block size b 512 bytes; inter block gap size g 128 bytes; number of blocks per track 20; number of tracks per surface 400. a disk pack consists of 15 double-sided disks. a. what is the total capacity of a track, and what is its useful capacity (excluding inter block gaps)? b. how many cylinders are there? c. what are the total capacity and the useful capacity of a cylinder? d. what are the total capacity and the useful capacity of a disk pack? e. suppose that the disk drive rotates the disk pack at a speed of 2,400 rpm (revolutions per minute); what are the transfer rate (tr) in bytes/msec and the block transfer time (btt) in msec? what is the average rotational delay (rd) in msec? what is the bulk transfer rate? f. suppose that the average seek time is 30 msec. how much time does it take (on the average) in msec to locate and transfer a single block, given its block address? g. calculate the average time it would take to transfer 20 random blocks, and compare this with the time it would take to transfer 20 consecutive blocks using double buffering to save seek time and rotational delay.

a)

b)

d)

e)

And if we convert using 1 s = 1000 ms we have"

The block transfer time btt would be given by:

And the average rotational delay would be given by:

f) For this case we can calculate the average time to locate and transfer adding the following time:

g) For this case we can calculate the time to transfer 20 random blocks like this:

And the time to transfer 20 consecutive blocks using double buffering would be:

Explanation:

Part a

For this case we need to calculate first the total capcity like this:

Where N represent the number of blocs per track, and if we replace we got:

And the useful capacity is given by:

Part b

For this case the number of cylinders correspond to the number of tracks.

Part c

First we can calculate the total cylinder capacity like this:

And the useful capacity is:

Part d

We can calculate the totals like on part d but we just need to multiply by 400 since that represent the number of tracks per surface

Part e

For this case we can convert the revolution per minute in revolutions per second like this:

And we can calculate the transfer rate like this:

And if we convert using 1 s = 1000 ms we have"

The block transfer time btt would be given by:

And the average rotational delay would be given by:

Part f

For this case we can calculate the average time to locate and transfer adding the following time:

Part g

For this case we can calculate the time to transfer 20 random blocks like this:

And the time to transfer 20 consecutive blocks using double buffering would be:

given the options, i would say your best bet is c. the modem supports up to 56 kbps, which is too low for video streaming. dial up modems use actual phone lines, which only can go up to 56 kbps as that's more than sufficient for traditional phone calls. this is also the reason why when a dial-up modem connects, you hear all those sounds. it's literally using the phone line to establish a connection.