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Microcomputer

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A microcomputer is a small and relatively inexpensive computing system.

Raspberry Pi 4 Model B - Side
Raspberry Pi 4 Model B - Side

It is defined by having a central processing unit (CPU) built from a single integrated circuit called a microprocessor. This CPU, along with memory and input/output (I/O) circuitry, is mounted on a printed circuit board (PCB). While they are much smaller than older mainframes or minicomputers, they are powerful enough to handle many tasks. Most microcomputers are designed to serve only one user at a time. Because of their size, they easily fit on or under a desk.

Early Personal Computers
Early Personal Computers

The mechanism of a microcomputer relies on the coordination of several key components. The microprocessor acts as the brain, processing instructions through logic gates. Memory, specifically Random-access memory (RAM), holds data that the CPU needs to access quickly. For a user to interact with the system, input and output devices are required. A keyboard allows a person to enter data, while a monitor displays the results.

PDP-11-M7270
PDP-11-M7270

Early systems often used audio cassettes for data storage to save programs. Later, more advanced systems used read-only memory (ROM) or EPROMs to store self-booting kernels. These stored programs allow the computer to load complex software automatically without needing an expert. This process transformed the device into an inexpensive turnkey system.

Microcomputers can be categorized by their intended use and complexity. Some are designed as embedded control systems. These specific machines may have no human-readable input or output devices at all. Others are designed for personal use and are often called personal computers (PCs). Many early models were sold as kits, such as the Altair 8800, which required assembly by the user. These early kits might have had as little as 256 bytes of RAM. As technology improved, microcomputers evolved into the desktop computers and laptops we use today.

The history of the microcomputer began with the development of the microprocessor. Before this, computers used many separate components for their CPUs. In 1973, a French team at the company R2E led by François Gernelle created the Micral N. This was the first available microprocessor-based microcomputer. It was designed for scientific tasks, such as measuring agricultural hygrometry. In the United States, the Altair 8800 served as an important early model for hobbyists. These early machines paved the way for the massive explosion of popularity in the late 1970s.

During the late 1970s and early 1980s, the industry saw significant growth. By 1979, many companies produced systems for small businesses. Companies like Cromemco, North Star Computers, and Processor Technology offered tools for accounting and word processing. This allowed small firms to automate tasks without the high cost of leasing a minicomputer. One famous example from this era is the Commodore 64.

Commodore-64-Computer-FL
Commodore-64-Computer-FL

It became the best-selling model of home computers of all time. Another group of highly successful 8-bit computers included the Apple II and the TRS-80 Model 1.

Home or Personal Computers from 1977 - Commodore PET 2001, Apple II, TRS-80 Model I, together called 'Trinity77' (edited image)
Home or Personal Computers from 1977 - Commodore PET 2001, Apple II, TRS-80 Model I, together called 'Trinity77' (edited image)

Technological shifts changed how users interacted with these machines. In the early days, users might have used a slow teletypewriter to communicate with a computer. As semiconductor memory became cheaper, engineers could dedicate 1 to 2 kilobytes of memory to a video display controller. This allowed for text displays or blocky color graphics on a common household television. The use of inexpensive logic chips, such as the 7400 series, also made it easier to build better user interfaces. Instead of using rows of switches to toggle bits, users could finally use a keyboard.

Today, the term "microcomputer" has mostly been replaced by "personal computer" or "PC." This change happened as the market standardized around IBM PC compatibles. The concept of the PC was used by IBM to differentiate its machines from small-business microcomputers and large mainframes. Modern technology has expanded the definition of a microcomputer even further. Today, laptops, tablets, mobile phones, and even pocket calculators are all considered microcomputers. They all share the same fundamental principle of using a microprocessor to perform tasks.

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File:Commodore-64-Computer-FL.jpg
Commodore-64-Computer-FL.jpg
File:Raspberry Pi 4 Model B - Side.jpg
Raspberry Pi 4 Model B - Side.jpg
File:Home or Personal Computers from 1977 - Commodore PET 2001, Apple II, TRS-80 Model I, together called 'Trinity77' (edited image).jpg
Home or Personal Computers from 1977 -...
File:Early Personal Computers.jpg
Early Personal Computers.jpg
File:PDP-11-M7270.jpg
PDP-11-M7270.jpg
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