PART 2 HOW HARDWARE
AND WINDOWS 98 WORK TOGETHER
COMPUTERS a re powerful el ectronic beasts, but they are also terri bly
ign orant. They knowlittle of the outside world. By itself, your PC doesn’t
know how to put images on the screen, howto print a document, or even what to
do with the keystrokes you peck into it.
There’s a good
reason for this. To create one piece of hardware that could automatically work
with any other piece of hardware would require filling it with information
about not only how to communicate with any other hardware that already exists,
but also with any hardware someone might come up with in the future. It can’t
be done.
That’s where
software comes in. You may already be accustomed to the idea of software as the
applic a ti ons, tools, and games you run on your com p uter. But spec i a l i
zed sof t w a re is also needed to tell the PC how to harness its awesome
power, how to use new and changing equipment that may be coupled to your PC,
and how to make sense of the millions of electrical signals coming in from
dozens of different sources.
If you look at
the PC as mu s cle and the sof t w a re as brains, there is one more el em ent
left. A s pec i fic chip set call ed the B I O S is the soul of your PC. The
instru cti ons wri t ten in the ch i p s’ m em ory to cre a te a basic inpu t /
ou tput sys tem a re what make your PC an IBM, a Gatew ay, a Dell , a Compaq, a
Hewlett-Packard, or a Packard Bell. Often called firmware to signal its status
halfway between hardware and software, the BIOS is the bridge between the rest
of the hardware and the operating system. It defines what those electrical
signals mean when they arrive at the PC, and it translates the equally baffling
signals from the computer into instructions for software and other hardware
connected to the computer.
It is this
marriage of sof tware and hardware that determines how healthy your PC is. In
the early days of the IBM PC, manufacturers of imitators of the IBM machine had
to re-create the functions of the IBM BIOS without outright copying the
instructions branded into the BIOS chips. And until clone makers got the hang
of it, there were a lot of “IBM-compatible” PCs that couldn’t display the
graphics an IBM could, interpreted keystrokes incorrectly, and sometimes were
so confused by the input and output going on that they went into a state of PC
catatonia. They crashed.
Today, the
relationships between hardware, software, and firmware have been so
standardized and purified that compatibility is no longer an issue. But the
BIOS and operating system remain the glue between the hard and soft sides of
the PC.
KEY CONCEPTS
bit, 16-bit, 32-bit A bit is the
smallest chunk of information a computer can work with—either the binary 0 or
1. 16-bit and 32-bit identify processors that can handle binary numbers up to
16 or 32 bits long. The more bits a processor can use, the faster it can make
computations and the more memory it can access easily. conflict, resource
conflict A problem that occurs when two or more hardware components try to use
the same PC resources for memory, interrupts, or direct memory access. direct
memory access (DMA) This system recourse allots a section of memory for
exclusive use by a component without having to go through the processor.
driver, device driver Code
written for specific peripherals, such as a video card or a printer, that
translates commands from software into the signals the peripheral can
recognize. expansion cards Circuit boards designed for specific functions, such
as handling sound or video, that plug into the PC’s motherboard.IBM-compatible
Originally, a PC designed to work with software and hardware the same way an
IBM PC would. This meant creating a BIOS that duplicated the functions of the
IBM BIOS without violating its copyright. Today the term is archaic because IBM
no longer sets the standard for PCs. Instead, PCs conform to standards set by
the use of Windows operating systems and Intel processors (Wintel). interrupt
controller A microchip that notifies the CPU that some piece of hardware has
sent a signal, in the form of a number, that it needs the processor to perform
some task. interrupt table A record of memory addresses linked to a specific
interrupt number. When an interrupt controller receives an interrupt, it looks
up the address associated with that number and instructs the processor to put
onto a stack the current address of the data the processors work with and to
start executing the code contained at the address found in the table. i n te
rrupt (IRQ), or inte rrupt re q u e s t A signal from a peripheral requesting
some service by the pro c e s s o r. interrupt return, or IRET instruction A
signal the processor sends to the interrupt controller telling it that the CPU
has completed the task requested by an interrupt. memory Where a computer
stores software and the data the software manipulates. Most commonly used to
refer to RAM, but also includes data storage on hard drives and other devices.
memory, extended That area of RAM that includes all memory addresses above 1 megabyte.
memory, low RAM with memory addresses from 0 to 640K. memory, upper RAM with
memory addresses from 640K to 1MB. m e m o r y, virtu a l H a rd drive space
that the operating system tells the processor to treat as if it were RAM.
memory address The specific location in RAM or virtual memory that can mark the
beginning of a section of code or data. motherboard The main circuit board of a
PC, into which the processor and expansion cards are inserted. peripheral Any
component, inside or external, that adds new hardware capabilities to the basic
design of a computer. For example: hard drives, printers, mouse.Plug and Play A
hardware and software design that is supposed to automatically configure system
resource settings. processor The main microchip in a PC. It carries out the
instructions of software by using other components, such as RAM or disk drives,
as needed.
thank and regards
cahyo nugroho
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