Basio IO - Hardware

1. (Extremely) Basic Computer Architecture

Hardware Components of a Computer

• Input - various devices allow us to input our instructions and our data to a computer. (Mouse, Keyboard, Touch Screen, Scanners, Sensors, Voice Recognition, OCR, MICR, Digital Cameras, Graphical Tablets)
• Output - various devices display the results of the computer's work to us (Monitor, Printers, Plotters, Speakers)
• CPU - the brain of the computer. Carries out our instructions and manipulates our data. 
• RAM - random access memory. Hold the programs (software) that instructs the computer on what output to produce and how to handle our input. It also holds our data (eg. Word processing documents) It erases when the computer turns off.
• Secondary Storage - Holds the software and data when the computer is turned off and when RAM isn't using it. Slower for the CPU to access than RAM, but it is cheaper than RAM. (Floppy disk, Hard Disk, CD ROM, zip disk)
• ROM - holds the instructions to boot that computer and the BIOS (Basic Input Output System). The boot instructions are essentially a self test and the directions to load the Operating System (OS). ROM can't (generally) be modified, unlike RAM and the Secondary Storage. It doesn't erase when the computer is turned off.

To learn more about the hardware pieces of a computer, you should take ICE3M - Computer Engineering.

Software Layers

In addition to hardware, there are some very important pieces of software (aka programs and applications) that are needed to make your computer run. We are going to learn how to write some very simple pieces of software in this class. 

• OS - the basic software. It handles a number of very important functions so that each application doesn't need to do it. eg. File Management, Input/Output. MS-DOS, WindowsME, Linux, Unix and MacOSX are all examples of Operating Systems.
• Computer Languages/Compilers - this is software that allows us to write other software. Examples of computer languages include Java, C++, C, Perl, Ada, Pascal and Visual Basic. Computer Languages use the OS to do various things for them.
• Applications - this is software that most people are familiar with. It allows us to enter data and manipulate it. Examples include Netscape, Word, Excel, Adobe Photoshop, etc.

2. CPU Pieces

The CPU is the central processing unit. It is also called the microprocessor or the 'brain' of the computer. The CPU is made of transistors. Transistors are one of the most significant inventions in computer hardware. They made desktop computers possible. They were created by Bell Labs in 1947.

2.1 ALU

• arithmetic logic unit
• part of the CPU
• handles the mathematical operations and boolean operations (eg. does x =1? boolean operations can either result in a true or false)

2.2 CU

• control unit
• part of the CPU
• gets the instructions that the CPU needs to process. It initializes operations in the ALU when it needs to. It also controls the flow of data around the CPU.

2.3 buses

• conductor wires or conduits that transport data inside the CPU. There are also buses to carry data around outside the CPU.
• buses have a certain bit-width. That is only a certain number of bits can travel in them at the same time.

2.4 primary memory aka L1 aka cache

• this is the memory that is directly on the CPU
• it is very small and can't hold much data, but any data that is here is very easily accessed by the CPU

2.5 secondary memory aka L2 aka cache

• this is memory that is fairly easily accessible by the CPU, but it isn't directly on the CPU
• it is slower to access than L1 memory.