Page 60 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Unit 3: Using Operating System

• Data compression utilities output a shorter stream or a smaller file when provided with a Notes
stream or file.
• Cryptographic utilities encrypt and decrypt streams and files.
• Launcher applications provide a convenient access point for application software.
• Registry cleaners clean and optimize the Windows registry by removing old registry keys
that are no longer in use.
• Network utilities analyze the computer’s network connectivity, configure network settings,
check data transfer or log events.
• Screensavers were desired to prevent phosphor burn-in on CRT and plasma computer
monitors by blanking the screen or filling it with moving images or patterns when the
computer is not in use. Contemporary screensavers are used primarily for entertainment
or security.

OS68 for Embedded Systems

OS68 overview: OS68 real-time operating system consists of a small configurable executive
kernel and a set of system tools such as debugging tools, target simulation tools. The executive
kernel is small in size about 11 kilo bytes in binary. It is simple due to its very limited set of
system calls. The design goals of OS68 are easy to use, efficient debugging tools and high
performance.

Easy to use: The number of system calls used in OS68 design are reduced compared to other
operating systems. 90 - 100% of the processes in a system need 6 or fewer system calls. It is
recommended to be restrictive when using tools other than the six basic calls. The six basic
calls are:

(a) Alloc: Allocate memory
(b) Free Buf: Return allocated memory to OS.

(c) Send: Send a message to a process.
(d) Receive: Receive selected messages, sleep if no selected message is available.
(e) Receiv_W_TMO: Like RECEIVE, but wake up again after a specified time if no message
is available.
(f) Delay: Sleep for a specific time.

Efficient debugging tools improve application development, and high performance is
due to configurable OS system according to specific application or specific processor
families.
(g) Process and its States: A process is an independent program running under real-time
operating system. A process running under a real-time operating system can find itself
in one of three distinctly different states.
(h) Running: The process is the one currently in control of the CPU. In a single process
system, only one process can be in this state at a time.
Contd...

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