Computers
as a Second LanguageComputers
as a Second LanguageComputer Fundamentals
WHAT
EXACTLY DOES THE OPERATING SYSTEM (OS) DO? PART
of the Operating System (OS) of a computer is contained in a ROM chip
which contains thousands of factory programmed instructions so that the
computer functions properly from the moment you turn it on. Remember,
these instructions are permanently set switches which never
change position whether the computer is off or on. The OS
immediately takes charge the instant you turn your computer on. One of
the first things the OS does is display the manufacturer's name and a
copyright message on the computer screen. Next, the OS performs a self
diagnostic test that includes checking all the RAM switches to make
certain they all work. You will see messages printed on the screen to
show the progress of the tests. It may seem hard to believe, but even if
one tiny RAM switch (a single bit) is not working, it is possible that a
software program loaded into RAM would not fully function or perhaps not
function at all! If any defective RAM switches are found, the OS will
display an error message on the screen. It's time to bring the computer
in for servicing and repair.After
the memory check, the OS will check to see what other devices are
present inside the computer such as a hard disk drive. The OS is
constantly monitoring everything that goes on in the computer.Different
computer manufacturers have their own Operating System ROMs. Apple has
proprietary Operating System ROMs for their Macintosh line of computers.
Earlier Macintosh computers contained 128 KB (kilobyte) ROM chips,
however their newer models contain 512 KB and 1 MB ROMs!. Commodore has
a proprietary 512 KB Operating System ROM chip (called Kickstart) which
is only available on their AMIGA line of
computers. IBM and IBM-compatible computers have smaller ROM chips, the
earliest XT machines had 40 KB ROMs, the AT machines had 64 KB ROMs and
all the newer machines have 128 KB ROM chips.Why
do Macintosh and AMIGA ROMs contain so much
more than IBM/compatible ROMs? It's because these newer proprietary
Operating Systems consist of very large programs stored in ROM chips.
The ROMs do much more than just starting the computer and checking what
other devices are hooked up to it. For example, much of the AMIGA's
multitasking Operating System is ROM-based (built into
the ROM) and it contains 512,000 bytes (512 KB) of program code! The
32-bit ROMs for the latest line of Macintosh computers also contain vast
amounts of Operating System instructions which give the Macintosh
computer its unique "look and feel".In
1981, IBM released the Personal Computer or PC. IBM did not write the
Operating System for the PC and they did not obtain an exclusive
copyright to use it. A key part of its Operating System is the
BIOS (Basic Input/Output
System) which was made available to any other
manufacturer who cared to license the rights to use it. When the PC
market proved to be lucrative, dozens of other companies started to
manufacture computers which were effectively identical to IBM's
machines. These machines are collectively known as IBM-compatibles or
IBM-clones. IBM-compatible manufacturers undercut IBM's prices and the
computer marketplace went crazy. Computer prices plummeted as
competition became fierce. IBM lost a great portion of the computer
buying market. |
