Hardware and Software

Hardware and Software

Much of computer science lies at the interface between hardware and software. Hardware
is electronic equipment that is controlled by a set of abstract instructions called software.
Both categories have a variety of subcategories.
2.1 Hardware
Computer hardware is typically electronic equipment that responds in well-dened ways to
specic commands. Over the years, a collection of useful kinds of hardware has developed:
1. Central processing unit (CPU) - a specialized integrated circuit that accepts certain
electronic inputs and, through a series of logic circuits, produces measurable compu-
tational outputs.
2. Random access memory (RAM) - stores information in integrated circuits that
reset if power is lost. The CPU has fast access to this information and uses it for
\short-term" memory during computation.
3. Hard disk drive (HDD) - stores information on magnetized platters that spin rapidly.
Information is stored and retrieved by a collection of arms that swing back and forth
across the surfaces of the platters touching down periodically to read from or write
to the platters. These devices fall into the category of \secondary storage" because
the CPU does not have direct access to the information. Typically, information from
the HDD must be loaded into RAM before being processed by the CPU. Reading and
writing information from HDD's is slower than RAM.
4. Other kinds of secondary storage - optical disks like CD's or DVD's where light
(lasers) are used to read information from disks;
ash memory where information is
stored in integrated circuits that, unlike RAM, do not reset if power is lost; all of these
are slower than HDD's or RAM.
5. Video card - is a specialized collection of CPU's and RAM tailored for rendering
images to a video display

6. Motherboard - a collection of interconnected slots that integrates and facilitates the
passing of information between other standardized pieces of hardware. The channels
of communication between the CPU and the RAM lie in the motherboard. The rate
at which information can travel between dierent hardware elements is not only deter-
mined by the hardware elements themselves, but by the speed of the interconnections
provided by the motherboard.
7. Interfaces - include the equipment humans use to receive information from or pro-
vide information to a computing device. For example, we receive information through
the video display, printer, and the sound card. We provide information through the
keyboard, mouse, microphone, or touchscreen.
In robotics, some of these terms take on expanded meanings. The most
signicant being the denition of interface. Robots are designed to interface
with some aspect of the physical world other than humans (motors, sensors).