Hardware Reference
In-Depth Information
Photo 1.2
A modern high-specification dual-BIOS PC motherboard
accolade that could be offered by the computer press was that a machine was
'IBM compatible'.
This chapter sets out to introduce the PC and provide an insight into the
architecture, construction, and operation of a 'generic PC'. It should, perhaps,
be stated that the term 'PC' now applies to such a wide range of equipment that
it is difficult to pin down the essential ingredients of such a machine. However,
at the risk of oversimplifying matters, a 'PC' need only satisfy two essential
criteria:
•
Be based upon an Intel 16-, 32-, or 64-bit processor, such as a 'x86, Pentium,
or a compatible device (such as a Celeron, Athlon, or Duron processor).
•
Be able to support the Microsoft MS-DOS operating system,
Microsoft
Windows, or a compatible operating system.
Other factors,
such as available memory size,
disk capacity,
and display
technology remain secondary.
To illustrate the progress in technology over the last 20 or so years, Table
1.1 shows typical specifications for various types of PC. However, before con-
sidering PC architecture in more detail, we shall begin by briefly describing the
basic elements of a microcomputer system.
Microcomputer
systems
The principal elements within a microcomputer system consist of a central
processing unit (CPU), read/write memory (RAM), read-only memory (ROM),
together with one (or more) input/output (I/O) devices. These elements are
