Computer Hardware

Parts of a Computer - Hardware

Key Terms

64 bit architecture
bus
cache memory
clock speed
CPU
hardware
I/O device
input device
modem
motherboard
output device
processor
RAM memory

Hardware is anything that will break if you drop it. Let's break down a computer's hardware system into manageable subdivisions: Input devices, output devices, the processor, and memory.

Input devices - This includes any device you use to send information to the processor. They include:

keyboard
magnetic data storage devices - These devices may be considered both input and output devices ... and are labeled I/O devices (for input/output). They include:
- disk drives (for 3½" floppy disks which are obsolete)
- hard drives (usually inside the case and not visible) ... also called the C: drive on a PC.
- removable storage (external hard drives)
solid state storage devices - USB thumb drives, Compact Flash cards (obsolete), SD cards (including micro SD), and others are all considered I/O devices. Some computers have done away with traditional hard drives and gone 100% solid state.
cable modem / DSL modem / faxmodem (I/O)
- A modem is used to communicate between computers. This is necessary for access to the Internet and email. With a fax modem, you can send anything you can print to a fax machine.
- A modem converts the computer's digital signal to analog (for line transmission) and vise versa. An analog transmission is a signal of varying voltage (basically, a wave). The word "modem" is a combination of the words modulate / demodulate.
Digital is 0 or 1 ... Analog is a wave (animation)
game console / joystick
mouse / trackball
screen pen (stylist) or light pen
touch pad
finger print / facial recognition / biometric scanner
touch screen (I/O)
Optical disks - CD's and DVD's - both audio and data CD's will run on a computer. There are 6 different kinds of optical devices currently sold with computers, ... they are:
- CD - ROM is read only (you can't change what is on the disk ... making it exclusively an input device). Virtually all computers can read this type of disk.
- DVD - ROM is the same as a CD-ROM, but with a much higher storage capacity so you can watch movies with this format.
- CD ± R is mainly an input device, but also allows a one time output (burn).
- CD ± RW (I/O) reads the CD, but also allows you to erase the data and write new data in its place ... like a thumb drive or hard drive can.
- DVD ± RW (and DVD -RAM) lets you burn your own DVD's that aren't copyrighted.
- Blu-ray Disc - This new standard uses a blue laser instead of red lasers used by the other optical devices on this list. Since blue light has a shorter wavelength than red light, you can compress more data on the disk without reading errors.
web cam / digital camera /digital video
- photographic film may be a thing of the past
sound cards (I/O) - voice input (microphones), ... but also speaker output
scanner
- used to digitize a picture (like a digital photocopier), but also is capable of "reading" text for word processing (OCR = optical character recognition).
- read barcodes
punch cards (obsolete)
floppy disk drives (obsolete)
cassette tape (obsolete)
manual setting of switches and wire connections (very, very obsolete) ... can you believe it? ... that was the way the first computers were "programmed"!

Output devices - This includes any device that accepts data from the processor.

monitors

A CRT (cathode ray tube) monitor is obsolete but it is a good place to start. A CRT works on the same principle as an TV picture tube, but without the tuning circuitry (which could be added by installing a TV tuner card). A beam of electrons is directed (by electromagnets) to the screen. Phosphors coated in the inside of the tube emit light if struck. To produce all the colors, phosphors of red, green, and blue are illuminated to different intensities.

Computer monitors are now flat panel LED or LCD screens. They are lightweight and use less energy than CRT monitors. How each of these monitors work was covered in earlier units. Also, touch screen technology changes the monitor to an I/O device. There are basically three different ways touch screens work (each covered earlier). When you touch the screen, your action changes resistance in an electrical path, changes capacitance, or alters acoustic waves.

Important features are:

Size (measured diagonally) 14”, 15”, 17”, 19", etc.

resolution 800 X 600, 1024 X 768, 1280 X 1024 (array of dots ... each dot is the combination of 3 colors ... red, green and blue). Each monitor has a maximum resolution setting assigned to it. A maximum setting of 1280 X 1024 means the monitor has 1280 rows of dots and 1024 columns of dots.

You can change the display resolution to make images appear bigger or smaller. When the monitor is set to the highest resolution, everything on the screen appears the smallest and each "dot" represents a pixel (picture element). That is, each dot is doing something different. However, if you move to a lower resolution, everything gets larger. Some adjacent "dots" will be doing the same thing and a pixel gets bigger (1 pixel = many dots). In some TV shows they conceal the identity of people by lowering the resolution so much that just a few pixels are used to display the person's face.

My monitor set to the maximum resolution 1280 x 1024

My monitor set to its lowest resolution 640 x 480

All the other colors you see are made by mixing these colors (red, green, and blue) at different intensities.

Click link 7.2.a to use a program that lets you mix RGB colors and change intensities to make other colors displayed on an LCD screen.

printers
- Dot matrix (obsolete) - These old printers used tiny solenoids as hammers to force ink on a ribbon onto your paper. They were very noisy and slow. Are you old enough to remember the heavy boxes of continuous paper sheets and the annoying guide strips on each side of paper that had to be removed?
- Ink jet (bubble jet) printers are the most common printer used in homes. These printers are quiet and produce images with high quality color and resolution. However, these printers are slow and ink cartridges are quite expensive. Several retailers offer a cheap refill service. The ink is forced out of the cartridge by thermal methods (tiny resistors vaporize some ink ... forming a forceful bubble) or by the mechanical push of a piezoelectric crystal.
- Laser printers are still mainly used for high volume, black/white copies. They are high quality and fast. Laser printers are mainly found in businesses and school settings. They work by transferring black toner to the paper via electrostatic charges in much the same way copy machines work.
speakers / headphones
projectors

The Processor

The Motherboard is a printed circuit board which holds slots for the CPU (processor), memory chips and expansion boards

A typical motherboard Courtesy Wikimedia Commons

All wiring between the components are made as part of the manufacturing process. Conducting and insulating materials are "layered" and etched to make microscopic electrical paths. The process used to manufacture circuit boards is called lithography.

CPU (central processing unit) - also known as the processor or microprocessor - This is the "workhorse" of the computer. It contains millions of transistors and is only the size of a soda cracker. The transistors act as lightning fast switches, and are used to hold and manipulate 0's (zeros) or 1's (ones).
- How fast the CPU works is determined by the Clock Speed of the computer. If a computer is rated at 800 MHz- (megahertz), that means the CPU is capable of taking in information at a rate of 800 million times a second (or it can manipulate a chunk of data every .00000000125 second) ! And they get faster and faster each year ... clock speeds in the Gigahertz (GHz) range are now the standard.
- 64 bit architecture! What does this mean? This refers to the amount of data the CPU can take in each cycle. For decades the standard was 32 bit architecture. This means the CPU could take in and operate on 32 binary characters at a time. Newer chip design has increased processing speed by moving to 64 bit architecture. This only works if the data pathways (bus) to/from the CPU are also constructed to handle this volume and the software running the computer is written to take advantage of this design.
  - One technique which has been around for years is called hyper-threading. Essentially this is a trick to make the operating system believe a single core is two separate cores.
  - The latest trend is to introduce 2 (dual core) or 4 (quad core) CPU's on the same die. This solves heat dissipation problems as well as a multitude of technical problems, mostly related to data transfer rates. If interested, click link 7.2.b to fill in the gaps
  - Most of the improvements involving chip design are to make sure the CPU doesn't have to wait for data. This is done by improving the bus (which is essentially the "highway" for data between components) and faster access to memory (like cache memory). Believe it or not, one constraint deals with the speed of light (the speed of electricity). If you put things in close physical proximity to each other, it cuts down on the travel time of an electrical signal (light travels 30 cm in a nanosecond). Said another way, if your computer has a clock speed of 1 GHz, in the time it takes the CPU to complete one machine instruction the output signal will travel about a foot in a wire. This can represent significant "down time" (data in the bus is not doing anything useful).
- Intel is the leading CPU manufacturer with AMD (Advanced Micro Devices, Inc.) a major competitor.
- Each year the CPU keeps getting more powerful and less expensive.
The Bus - Data is constantly moving through components of your computer. The "highway system" between devices is known as the bus. One of the main jobs of the CPU is to act like a cop at an intersection and direct traffic. It has to find the fastest and most efficient way to move data around. The cars are the data streams, and the roads are the bus. Each computer has many different "buses", depending on which device we talk about. Buses can be considered internal if they interact between devices inside the casing ... and external if they connect to devices outside the casing. Some examples are:
- PCI local bus - the link between the expansion slots and the processor.
- USB (universal serial bus) - provides an interface between software and hardware so the system can tell how a connected device should work (plug and play).
- HDMI

Memory

When you run software (say a word processing program), you move the stored program from the hard drive to RAM memory where the CPU can make use of it. When you write your letters with the program, the data also gets stored in RAM. If the power goes out before you have had a chance to save the information to a flash drive or the hard drive, all your data is lost. The point is, you can think of the hard drive as a warehouse for data storage and RAM as the place all those zeros and ones are put into action.

The CPU needs to shovel data (0's or 1's) in and out very quickly. The data stored on a hard drive takes too much time to access. To quickly access data the CPU needs, the system relies on an "electronic" way of storing all those 0's and 1's. This is called RAM - or random access memory. However, even this method can be slow, so computer designers store "frequently used" data in a much faster (and more expensive) memory called cache memory (which is subclassified as L1 and L2). Once stored in memory, the CPU can quickly move data in and out.

Win XP users needed at least 512 MB of RAM.
Computers running Windows 10 typically require a minimum of 2 GB (but more is better).

Since the field of computer development is changing so rapidly, new (computer related) terms are often not found in conventional books. Link 7.2.c is a great place to brush up and stay current on the latest technology.

Blurred Lines ... what is a computer these days?

Not too long ago people used computers at home or at the office and they looked like this:

.... and you had a "modern" cell phone. And it looked like this:

Courtesy Wikimedia Commons Courtesy Wikimedia Commons

But that is NOT the case anymore! Smart phones are computers which have more data crunching power than the top-of-the-line desktop computers had a decade ago. You can now video chat with people with your desktop/laptop computer (Google Hangouts, Skype, FaceTime) and you can access the Internet on your smart phone. Notebooks, iPads, and tablets are somewhere in the middle. The point is, the vision of what a computer actually is (and looks like) has evolved enormously in a very short time. All these things are computers!