Contact US

Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

don't understand how system hierarchy works.

don't understand how system hierarchy works.

don't understand how system hierarchy works.

Hello, I posted this in the qbasic forum because its an old dos program and I have a dos related question that also pertain's to a compiler such as qbasic.  In an paragraph in my 'Troubleshooting, maintaining, repairing pc's' book it explains (somewhat) that if you use say print "hello" that the qbasic program(compiler) doesn't access the hardware directly it accesses msdos.sys the kernel and then that accesses the bios which inturn displays the word, and this goes for any qbasic command. Why is this? how does it work? why is it set up like this?

RE: don't understand how system hierarchy works.

In days of yore, when programmers were Real Programmers, everyone accessed the hardware directly and wrote in binary by toggling instructions into the machine.

Since those happy days, operating systems have come along that insulate the programmer from the need to write in binary.

Instead you use a compiler or interpreter for the language you want to use.

In other words, it's a lot easier than programming down at the bare metal.

You could still use instructions to directly access the hardware in operating systems other than NT & XP such as dos, win95, win98.

For security reasons, NT and XP make this much more difficult.

So there's a sort of pyramid: your program, the operating system, the bios, and the hardware.

This reduces (in theory) the amount of effort you put in to writing a program.

RE: don't understand how system hierarchy works.

hm so the os must have done most of the work for you in other words, or at least a good chunk of it. So for example the qbasic statement print "hello" would go to a routine(in memory) in the dos kernel that take's input and displays it on screen, So when the programmers of qbasic first made their "print" command or what have you they didn't have to do as much programming? So its like using dos services..

RE: don't understand how system hierarchy works.


The operating system reduces the amount of work you have to do.

The exceptions to this are instructions like peek & poke that will access memory or i/o addresses directly and don't use the operating system at all.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members! Already a Member? Login

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close