Answer:(1) To manage the computer's resources, which includes central processing unit, memory, disk drives, and printers, (2) To establish a user interface

(3)To execute and provide services for applications software.

The old mainframe computers have

(1) low memory sizes

(2) slower connectivity speed

(3) Larger sizer

(4) low sophistication.

Explanation: Operating system is a system software that manages the computer resources,helps to establish user interface and it helps to provide services for application softwares.

Operating system software includes WINDOWS X,WINDOWS 7,WINDOWS 8,LINUX,etc.

Mainframe computers are computers used by large multinational companies for processing bulk data. Old mainframe computers were produced by IBM(INTERNATIONAL BUSINESS MACHINE) in the year 1952 they are classed two scientific and commercial mainframe computers with different information although they had some incompatibilities. Old mainframe computers are large in size with low processing speed, sophistication and storage compared to present day system.

3 0

4 years ago

It takes 2 seconds to read or write one block from/to disk and it also takes 1 second of CPU time to merge one block of records.

Alexxx [7]

Answer:

Part a: For optimal 4-way merging, initiate with one dummy run of size 0 and merge this with the 3 smallest runs. Than merge the result to the remaining 3 runs to get a merged run of length 6000 records.

Part b: The optimal 4-way merging takes about 249 seconds.

Explanation:

The complete question is missing while searching for the question online, a similar question is found which is solved as below:

Part a

For optimal 4-way merging, we need one dummy run with size 0.

Merge 4 runs with size 0, 500, 800, and 1000 to produce a run with a run length of 2300. The new run length is calculated as follows $L_{mrg}=L_0+L_1+L_2+L_3=0+500+800+1000=2300$
Merge the run as made in step 1 with the remaining 3 runs bearing length 1000, 1200, 1500. The merged run length is 6000 and is calculated as follows

$L_{merged}=L_{mrg}+L_4+L_5+L_6=2300+1000+1200+1500=6000$

The resulting run has length 6000 records.

Part b

For step 1

Input Output Time

Input Output Time is given as

$T_{I.O}=\frac{L_{run}}{Size_{block}} \times Time_{I/O \, per\, block}$

Here

L_run is 2300 for step 01
Size_block is 100 as given
Time_{I/O per block} is 2 sec

$T_{I.O}=\frac{L_{run}}{Size_{block}} \times Time_{I/O \, per\, block}\\T_{I.O}=\frac{2300}{100} \times 2 sec\\T_{I.O}=46 sec$

So the input/output time is 46 seconds for step 01.

CPU Time

CPU Time is given as

$T_{CPU}=\frac{L_{run}}{Size_{block}} \times Time_{CPU \, per\, block}$

Here

L_run is 2300 for step 01
Size_block is 100 as given
Time_{CPU per block} is 1 sec

$T_{CPU}=\frac{L_{run}}{Size_{block}} \times Time_{CPU \, per\, block}\\T_{CPU}=\frac{2300}{100} \times 1 sec\\T_{CPU}=23 sec$

So the CPU time is 23 seconds for step 01.

Total time in step 01

$T_{step-01}=T_{I.O}+T_{CPU}\\T_{step-01}=46+23\\T_{step-01}=69 sec\\$

Total time in step 01 is 69 seconds.

For step 2

Input Output Time

Input Output Time is given as

$T_{I.O}=\frac{L_{run}}{Size_{block}} \times Time_{I/O \, per\, block}$

Here

L_run is 6000 for step 02
Size_block is 100 as given
Time_{I/O per block} is 2 sec

$T_{I.O}=\frac{L_{run}}{Size_{block}} \times Time_{I/O \, per\, block}\\T_{I.O}=\frac{6000}{100} \times 2 sec\\T_{I.O}=120 sec$

So the input/output time is 120 seconds for step 02.

CPU Time

CPU Time is given as

$T_{CPU}=\frac{L_{run}}{Size_{block}} \times Time_{CPU \, per\, block}$

Here

L_run is 6000 for step 02
Size_block is 100 as given
Time_{CPU per block} is 1 sec

$T_{CPU}=\frac{L_{run}}{Size_{block}} \times Time_{CPU \, per\, block}\\T_{CPU}=\frac{6000}{100} \times 1 sec\\T_{CPU}=60 sec$

So the CPU time is 60 seconds for step 02.

Total time in step 02

$T_{step-02}=T_{I.O}+T_{CPU}\\T_{step-02}=120+60\\T_{step-02}=180 sec\\$

Total time in step 02 is 180 seconds

Merging Time (Total)

Now the total time for merging is given as

$T_{merge}=T_{step-01}+T_{step-02}\\T_{merge}=69+180\\T_{merge}=249 sec\\$

Total time in merging is 249 seconds seconds

5 0

3 years ago

Which relation is created with the primary key associated with the relationship or associative entity, plus any non-key attribut

konstantin123 [22]

Answer:

- Transform binary or unary M:N relationship or associative entity with its own key.

Explanation:

Transform binary relation is described as the method through which a decimal can easily be converted into binary while the unary relationship is described as a relationship in which both the two participants occurs from the same entity.

In the given case, 'transform binary or unary M:N relationship' can be created using 'the primary key linked with the relationship plus any non-key aspects of the relationship and the primary keys of the related entities' as it displays the existence of a relationship between the occurrences of a similar set of the entity i.e. associative entity here.

5 0

3 years ago

Light travels at 3 × 108 meters per second. A light-year is the distance a light beam travels in one year.Write a PYTHON program

Volgvan

Answer: This is a python code

def lightyear():

rate=3*100000000 //speed of light

seconds=365*24*60*60 //number of seconds in 1 year

return str((rate*seconds)/1000)+" km" //distance=speed x time

print(lightyear()) //will print value of light hear in kilometers

OUTPUT :

9460800000000.0 km

Explanation:

In the above code, there is a variable rate, which stores the speed of light, i.e. distance traveled by light in 1 second which is in meters. Another variable is seconds, which store the number of seconds in 1 year, which is no of days in 1 year multiplied by the number of hours in a day multiplied by the number of minutes in an hour multiplied by the number of seconds in a minute. Finally, distance is speed multiplied by time, so distance is printed in kilometers and to convert distance in kilometers it is divided by 1000.

4 0

3 years ago