What Is System Programming?

Micah MacBride

All programmers write executable code for computers, but what sets system programmers apart from application programmers is the purpose of the software they write. Application programming produces software that makes a computer's hardware generate something for the user, be it a spreadsheet or the graphics for a game. System programming produces software that accesses and controls the inner workings of a computer's hardware and operating system.

Software engineers understand operating systems.
Software engineers understand operating systems.

Application programming generally involves issuing system commands to utilize the basic functions of a computer's hardware and operating system, such as storing a particular piece of data in the computer's physical memory or a file on the hard drive. These kinds of programs are not concerned with details of how the hard drive or physical memory are working. Conversely, system programmers concern themselves with the details of how an operating system and hardware components work. This allows them to build the software that defragments hard drives and checks the integrity of a computer's physical memory.

System programmers need a detailed understanding of programming code.
System programmers need a detailed understanding of programming code.

In addition to being able to build such tools, system programmers are typically experts in the core functioning of operating systems. All programmers are familiar with system calls, thread management, and input/output handling, but system programming requires the software engineer to be able to manipulate these operating system mechanisms. This allows a system programmer to perform specialized installations and automate system maintenance tasks.

Knowledge of an operating system's core is also necessary in order to maximize an application's performance on a particular hardware configuration. For example, very busy online retailers need their websites and transaction processing systems to run as efficiently, and reliably, as possible. Using his or her knowledge about the internal mechanics of operating systems and hardware components, such as how to make a particular operating system optimize its thread handling or which algorithms run fastest on which hardware components, a system programmer can help fine tune an application's performance.

This detailed access to the inner workings of hardware and operating system components requires system programming to be done in a language that allows this kind of low level hardware access. Languages such as Java®, Python™, or Ruby on Rails® are what programmers refer to as high level languages. This means that they make application programming easier by not making the programmer handle the fine details of hardware management. System programming requires exactly this kind of access, so system programmers use a low level language such as C or C++.

Systems programmers are concerned with the functioning of hardware components like hard drives.
Systems programmers are concerned with the functioning of hardware components like hard drives.

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Discussion Comments


@Markerrag -- I am not sure if it is harsh or not, but it is hard to deny that some (certainly not all) companies that deal with applications programming rush things out the door and plan on fixing it later.

Take video game consoles. Back when programs were written onto cartridges and could not be changed, you don't get the patches and updates to fix problems that you do now. What is the difference? Consoles are typically online and can be updated with ease. So, some game designers rush things out the door and repair problems later. It stinks, but that is the way it is.

You do have some patches to applications software, but not nearly as much. Hardware drivers and new BIOS "flashes" are times when you are updating those programs. But I do believe you will find far more comprehensive testing in the systems programming world. I am talking about on average, of course, as there are plenty of applications companies that take quality control very seriously.


@Logicfest -- I don't know if that is fair. It is not like applications programmers are lazy and release half done code out the door because they know they can just patch it later. To be fair, applications are usually a lot bigger than systems programs and there are more things that can go wrong. Also, there are so many pieces of hardware that applications programmers have to deal with that that conflicts can pop up often (will this program work with that sound card or that graphics card?)

Finally, let us not forget that a lot of updates are necessary because hackers find ways to break security protocols and cause trouble. Systems programmers don't have to worry about that so much.


Wow. Remember when C and C+ were considered high level languages? My how things have changed.

Anyway, one of the things that makes system programmers different is that there stuff has to work almost flawlessly out the door. The applications guys can always issue patches and fixes down the road and that happens all the time.

In the systems world, though, just imagine how big of a fail it would be to release a BIOS that wouldn't work and would cause computers not to boot? You can't fix that with a patch. That is a major problem that can ruin a company.

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