bit 01: computer hardware basics


bit 01: computer hardware basics

how the essential hardware of a computer works together to function as parts of a whole

In our modern digital age, the definition of “computer” has become much more than just a PC or Mac. The rise of smartphones and tablets as ‘mini’ computers revolutionized how accessible and transportable these devices can be. What is fascinating is that the architectural structure of a computer has not changed much since the 1940’s, even as the physical properties become modernized.

essential hardware

The brain of every computer is the CPU, or Central Processing Unit, which controls the essential functions of the device using stored program instructions. The CPU does arithmetic, moves data around, and controls operations independently of human users. It is broken up into two main processor components: a control unit (CU) which orchestrates the execution of instructions, and an arithmetic and logical unit (ALU) responsible for all mathematical and logical computations. It uses an internal clock which functions at billions of hertz per second, meaning how many ‘clock cycles’ it can perform in a given second. The faster the clock cycle, the more instructions the CPU can execute.

Instructions are stored on the a memory device commonly known as RAM, or Random Access Memory. It stores the data which the CPU is currently working on, as well as instructions on what to do with that data. Different computations allow the same CPU to run various stored programs, like Microsoft Word and Adobe Photoshop. However, RAM is volatile, meaning it does not store this data once the computer is turned off and secondary storage is necessary to save files.

A more in-depth description of CPU and RAM can be found here, but the image below visually depicts the basic construction of any type of computer.

Secondary storage can come in two forms: a hard drive or SSD (solid state disk). Disk space is cheaper than RAM, but the retrieval process is slower. The hardware in either type of disk and software in the computer’s operating system create the basic organizational structure of how information is stored. These architectural devices are connected in the computer by a set of wires called buses. You may be familiar with a USB, or Universal Serial Bus which is essentially a transportable memory device with its own hard drive. Whether it is through a circuit board or portable USB, a bus is a required intermediary connecting the CPU to the memory unit, and then to the input and output devices.

physical construction

The CPU uses logic gates to perform functions, which compute a single output value based on two input values. It receives the signals in the form of an electric current, compares them, and translates the output instructions into a language the computer understands, in the form of 0 or 1. The current is controlled by a transistor which switches on or off based on the voltage. Logic gates are created on integrated circuits, or chips, which have no discrete pieces or conventional wires. They do, however, perform the same functions as larger circuit boards. If you have ever looked at the inside of a computer, you may have seen an integrated circuit much like this:

Although the basic structural elements like the CPU and RAM have not changed since ancient computers, the level of computing power has increased drastically, allowing for faster internal processing. Moore’s Law states that the exponential growth of computing power doubles about every year, based on the number of transistors able to be manufactured on a single integrated circuit. Processors can also use more transistors by placing more than one CPU on a chip, or having multiple processor chips, resulting in a computer able to perform billions of computations per second.

These are the most basic hardware functions of a computer; more in-depth topics to follow.