Fourth Case Study in OS

Third Case Study in OS

Time-sharing - is the sharing of a computing resource among many users by means of multiprogramming and multi-tasking.

Using system resources (CPU, disk space) without proper accounting – This is one of the problems occurred when you use a time-sharing environment.

Causing the printer to mix output by sending data while some other user's file is printing - This is one of the problems occurred when you use a time-sharing environment.

Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine?

No, because developing a system that supported multiple users at the same time was a completely different concept. The user machine is defined by the combination of the time-sharing hardware running in user mode and the software which controls input-output. If the hardware is arranged in such a way that calls on the system have the same form as the hardware instructions of the machine then the distinction becomes irrelevant to the user; he simply programs a machine with an unusual and powerful instruction set which relieves him of many of the problems of conventional machine-language programming.

Second Case Study in (OS)

• Handheld Computer - (also known as a handheld device, handheld computer or simply handheld) is a pocket-sized computing device, typically having a display screen with touch input and/or a miniature keyboard.  According to Wikipedia.
• Manager in a supermarket - A supermarket manager may assume many different duties, such as supervising employees and store operations, taking inventory and ordering products, performing administrative and human resources work, or engaging in safety inspections and loss prevention.  To make the work of supermarket manager easier he/she needs a device that  has a good quality, affordable and handy .

The Handheld computers is one of the best example of a device that helps a lot in your outside works or office works. This gadget is very handy you do not need a large bag in order to carry it. It can be placed in pocket or in a pouch. This gadget may use by a  supermarket managers in taking inventories , doing follow ups in their products, scheduling meetings and other computer related works of the manager. Further handheld computers were capable of performing around 80 percent of the tasks achieved by desktop computers.

• Newspaper reporter - A newspaper reporter do a lot of jobs like finding scoops, being journalist, researcher and specially presenting their reports in public. In order for the reporter to have an easy storing information in a certain event rather than using a bond paper or other kinds of papers. The best gadget to be used was the Handheld computer  “palmtop” because doing something like writing some information  and after you can transfer it in the gadget to avoid data loss . The files that stores in your handheld computer is accessible anytime, anywhere. That’s why now a days when we watched television  reports. We noticed a gadget that most of the reporters carries and that was an example of a handheld computer.     

First Case Study in OS

Case Study #:  1

·         Batch Systems - was very expensive. The input side of the user interfaces for batch machines were mainly punched cards and with the limited exception of the system operator's console, human beings did not interact with batch machines in real time at all.

Example:  IBM 029 card punch.

·         Interactive Systems - the user and the computer interact or communicate with one another also the operating system allows any application to be run at any time. More important applications can be given priority to run before other, less important applications.
Example:  Modern Computers (Personal Computers)

·         Real-time systems - These systems are where data and instructions are processed at the same time it is generated further its application can be considered (within context) to be mission critical.

Example: Flying planes or controlling missiles. Delays in processing instructions can lead to accidents.

·         Hybrid Systems – are dynamical systems with interacting continuous-time dynamics. Hybrid systems have been used to model several systems, including physical systems with impact, logic-dynamic controllers, and even Internet congestion.

Example: Hybrid computer – which exhibit features of analog computers and digital computers.

·         Embedded Systems - Embedded systems are controlled by one or more main processing cores that are typically either microcontrollers or digital signal processors (DSP).

Example: portable devices such as digital watches and MP3 Players, traffic lights and factory controllers.