EVOLUTION OF THE OPERATING SYSTEM

EVOLUTION OF THE OPERATING SYSTEM
Operating systems as they are known today trace their lineage to the first distinctions between hardware and software. The first digital computers of the 1940s had no concept of abstraction; their operators inputted machine code directly to the machines they were working on. As computers evolved in the 1950s and 1960s however, the distinction between hardware such as the CPU and memory (or Core as it was called then) and the software that was written on top of it became apparent.
Batch job systems in the 1960s
• IBM 360 series, and JCL (Job Control Language):
Batch operating systems could only execute one program at a time. The operating system maintained a queue of user programs which had been submitted and were waiting for a chance to execute. Each user program which needed to execute was called a "job". A human "operator" watched over the queue with the ability to move some jobs to the front or back, or kill a job which got hung or ran too long. Some users had higher priorities than others.
Time sharing systems in the 1960s and 1970s
• CTSS / ITS
• Multics / Unix
Unix was the first successful "timesharing" operating system. In a time-sharing system, multiple programs appear to execute at once, but in reality, the fast-working computer processor is alternating quickly among several different programs; at any one instant in time, only one program executes, with all others waiting. To users, the illusion is that they have the processor to themselves, because each program (called a "process" while it runs) seems to run simultaneously with others. In a timesharing operating system, the operating system is responsible for "scheduling" each process (determining when and how long each process gets to run and making sure that every process regularly gets some time in which to run).
The dawn of the Personal Computer in the 1970s and 1980s
The big three:
• Tandy/RadioShack TRS-80
• Commodore PET
• Apple II
In the late 1970s and early 1980s the concept of someone owning a computer and having it sit on a desk at their house (or place of business) became feasible. A common example of one of the first "personal computers" was the Altair. Computers in that generation, lacking a keyboard or even a standard display, were more of a hobbyists' toy then actual PCs that we know today. The Homebrew Computer Club was one example of the computer clubs that sprang up in this era.
Computers as we know them today evolved from these hobbyist machines into something that was more accessible to consumers. The "big three" manufacturers that ignited this era included Tandy/Radio Shack, Apple Computer and Commodore. Conspicuously absent was IBM, who would not enter the PC market until the early 1980s.
As hardware evolved and desktop computers became common, so too did the operating systems that ran on them.
GUI driven operating systems in the 1980s and 1990s
• Xerox PARC's Alto (the inspiration for the GUI)
• Apple Macintosh
• Microsoft Windows
Operating systems today 2007-Till date.
Except for small embedded computers, most operating systems today perform timesharing similar to the strategy used for the original Unix operating system. But in fact, modern operating systems do it on two levels:
1. the processor is shared among each process (running program)
2. the processor may also be shared among multiple threads within one process, allowing a single program to appear to do several things simultaneously
REFERENCE
• "Operating System Market Share". Net Applications. http://marketshare.hitslink.com
• http://en.citizendium.org/wiki/Operating_system
• The evolution of the MVS Operating System. IBM J. Research & Development. http://www.research.ibm.com/journal/rd/255

DATALINK UNIVERSITY COLLEGE
DEPARTMENT OF COMPUTER SCIENCE AND INFORMATION SYSTEM
CSIS 370 OPERATING SYSTEM
RESEARCH ASSIGMENT:

SUBMITTED TO
Mr. Ben Bright Benuwa.

NAME: Nyesom Hachikaru Prosper
ID: CS09100128.
Level: 300.
Date: 6th January, 2013.