Category: 

What is Job Control?

Article Details
  • Written By: M. McGee
  • Edited By: Lauren Fritsky
  • Last Modified Date: 06 September 2016
  • Copyright Protected:
    2003-2016
    Conjecture Corporation
  • Print this Article
Free Widgets for your Site/Blog
Due to synthetic materials and furnishings, new homes burn about five times faster than those built 30 years ago.  more...

September 25 ,  1789 :  The US Bill of Rights was adopted.  more...

Job control is the term for managing various actions on a computer system. Computers are capable of doing multiple things at the same time, but in many cases, only a single process can operate in a given area at any one time. Computers use a job control system to manage their tasks, letting one process use resources in one area while another uses resources in a different area. These systems monitor the priority of operations and keep important tasks running faster and less important tasks in the background.

Job control systems developed early on in the design of modern computers to alleviate speed problems. In many early systems, the central systems of the computer were more than capable of speeding through the tasks given to them. The speed problems happened in the communications with peripheral systems. Not only were the systems slower, but the transferal time between the systems groups was quite long. Additions to peripheral hardware, such as buffers and cache systems, only made certain processes faster and didn’t solve the problem.

Multitasking was an early attempt at job control. The computer was given a new system that kept track of active and inactive jobs. When a system was too busy to handle a new job, it was put into an inactive queue. When the hardware was able to take a new process, the highest-priority process would be made active. This process would then move into the hardware.

Ad

The problem with this system was in its decentralized nature. While a single queue held all the active and inactive processes, information pertaining to the hardware came from the hardware itself. The driver for the hardware would report whether it was available or not to the scheduler—if a process entered an error state and continued to use the hardware, it would never become available. In addition, some processes only needed the central processor or a certain peripheral; this would tie up the entire system until those processes ended. In order to combat this problem, modern job control systems were designed.

Job control focuses on the idea of pre-emptive computing. Each process is given an overall priority and, occasionally, secondary priorities relating to certain systems. The computer’s scheduler maintains the queue of processes. When one process comes up that is more important than one that is currently active, the active one will suspend and the new process will take over. When the suspended program is the most important process, it will start up again.

Ad

You might also Like

Recommended

Discuss this Article

Viranty
Post 3

@Hazali - While I do agree with you, don't forget that computers aren't flawless either. The article mentions this as well, referring to it as a "decentralized" nature.

Overall, whether we're multitasking or not, I think one advantage that we have over computers is that we're not "programmed" or "computerized", so to speak. We have thoughts and feelings, which dictate or daily lives. And try as we might, we won't always have a set schedule.

Euroxati
Post 2

@Hazali - I definitely agree with you. Besides, even though computers have flaws, it's in a much different sense, so to speak.

However, when we try to multitask or get what we need to get finished, things don't always work out according to our "perfect" plan.

Things can come up in life that interfere with our schedule, or we may realize that we don't have enough time to complete what it is that we're trying to complete.

Hazali
Post 1

Speaking of job control and multitasking, in my opinion, it really shows how much technology has advanced in this day and age, and how complex computers have become. After all, even though we as humans have the ability to multitask, there are flaws in our system, so to speak.

Post your comments

Post Anonymously

Login

username
password
forgot password?

Register

username
password
confirm
email