software requiring hard disk space

[rookie1010]

Hello

I was wondering why does software require x MB of free hard disk space for operation over the y MB of space required for installation?

 

[KSoD]

Software requires more for install then operation as it is zipped up in the .exe or in the setup.
It requires stuff for operation since install doesn make it run. That only lets your system know you installed it. After you click the application to start it then uses system resources to run. It has to be stored in RAM to run.

 

[rookie1010]

thanks for the reply

that explains the RAM bit, but once installed it should just require RAM memory not hard disk memory, correct?

 

[Amd2800]

it requires both

 

[rookie1010]

why does it require the hard disk memory at execution time. i thought all the code and data regions are mapped to the RAM?

 

[KSoD]

Not everything that the application uses is stored on the RAM. Some applications are just too big to store all the info needed in the RAM of a PC. Plus depending on the amount of RAM a PC has it might not even contain enough to do so. So the RAM gets the basics that the application has started up. It then directs to the HDD to where the apoplications is located and that is how it mainly works. There are variations. Sometimes full applications can be stored. Other times they only run off of the HDD. It al depends on how the program was written.

 

[rookie1010]

thanks for the reply

you are talking about virtual RAM memory, correct?

you mean to say that the programmer progams in his program that the program is going to use hard disk memory or virtual memory(?)?

 

[KSoD]

It all depends. Sometimes you will notice that a application takes upwards of 20MB to run. Now if you only have 256MB of RAM you cant use over 20MB for jsut 1 application. So the OS has to determine what is going to be used from RAM and what isnt. So it is decided from the programmer and also from the settings of the OS. It isnt always Virtual Memory since i have mine off. I also have 1.5GB of RAM to use. So if a programmer knows that his application is resource heavy, Norton for example, Then they would state that 20% is used by system resources and the other 80% is used by the system. Like i said it all comes down to your system settings and how much RAM you have. Nothing out there will only use 1 or the other. They all use some of both.

 

[rookie1010]

thanks for the reply

i did not understand what you meant by
"Then they would state that 20% is used by system resources and the other 80% is used by the system."?

 

[KSoD]

What i mean is that they would put it in the programming that a certain percentage would use the system resources. AKA RAM and processing power. The other percentage would use HDD resources.

The major problem with writing programs is that you have to make it useable by all people. Since not everyone has 1GB or more of RAM you have to make it suitable for less resources. Which means that it would have to use more of the processor and HDD. So if you only have 32MB of RAM it would eat all 32MB trying to run that application. It would only use what is necessary and the rest would be used by the processor and HDD.