Definition: chip

(1) A bit in a spreading signal. See chip rate.

(2) (C.H.I.P.) World's first $9 computer. See CHIP computer.

(3) (ChIP) (CHromatin ImmunoPrecipitation) A test of the interaction between the DNA and proteins in a human cell. See ChIP on chip.

(4) (CHIP) (Children's Health Insurance Program) See healthcare IT.

(5) (CHIP) (Connected Home over IP) See Project CHIP.

(6) (computer chip) A set of microminiaturized electronic circuits fabricated on a thin slice of semiconductor material. The most amazing technology, the chip is the driving force in this industry, and it resides in nearly every electronic device on the planet. Officially an "integrated circuit" (IC), unpackaged ICs look like tiny "chips" of aluminum. While most chips contain only digital circuits, some are analog only, and some are mixed analog and digital (see mixed mode). Billions are made every year, and the various types are described below.

Raw chips are approximately 1/30" thick and from 1/32" square to the footprint of a postage stamp and sometimes larger. The primary element in a chip is the transistor, and small chips contain tens of thousands, while large chips have billions. It is actually only the top one-thousandth of an inch of a chip's surface that holds the active circuit layers, and the action that takes place every second is truly unbelievable (see active area). Although chips may be formed from other materials, silicon is the primary element (see silicon). To learn how the chip is made, see chip manufacturing.

Types of Chips by Function
The central processing unit (CPU) is the primary logic chip in every computer or computer-based device. Also called a "microprocessor," the CPU is a general-purpose machine because it follows instructions in software and thus can perform countless different tasks. If there is no CPU in a device, it cannot really be called a computer. See CPU and microprocessor.

Special-Purpose Logic
A special-purpose "application specific IC" (ASIC), performs a fixed set of steps that cannot be changed. ASICs are smaller and faster than microprocessors and less expensive but only when manufactured in large volume. See ASIC.

Partially Fabricated Logic
All logic chips start out in a semiconductor fabrication facility. However, there are logic chips that are only partially finished at the plant and programmed to completion by the customer, who becomes the circuit designer. See PLD.

Flash Memory and RAM
Flash memory chips store data permanently and are used for storage and firmware. RAM chips store data temporarily and are the computer's main memory. RAM is either dynamic (fast) or static (faster), but both are volatile and lose their content without power (see dynamic RAM and static RAM). See RAM, firmware, ROM, EEPROM, flash memory, early storage and early memory.

Graphics Processing Unit (GPU)
Executing billions and trillions of calculations per second, the GPU converts the digital images in the computer into pixels for the screen. High-end GPUs are required for gaming PCs in order to render fast video sequences in a realistic manner. They are also used for AI and other applications that require massive amounts of computations in parallel. See GPU, GPCPU and AI chip.

Microcontroller (MCU)
An MCU is a single chip that contains the CPU, flash storage, RAM, input/output control and a clock (pulse generator). Billions are used every year in myriad products. See microcontroller.

System-on-Chip (SoC)
An SoC is an MCU and more. For example, in a smartphone, the SoC includes all the MCU components along with a GPU, image processing section and neural processing unit. See SoC.

Analog/Digital and Signal Processing
"A/D converters" and "D/A converters" convert real signals (audio, video, voltage, etc.) to the digital world. A related chip is a "digital signal processor" (DSP), which performs fast instruction sequences commonly used in such applications. See A/D converter, mixed mode and DSP.


The Chip Revolution
In 1947, the semiconductor industry was born at AT&T's Bell Labs with the invention of the transistor by John Bardeen, Walter Brattain and William Shockley. Fabricated from solid materials that could change their electrical conductivity, the transistor replaced the hot glass tubes in radios, TVs and computers. Today, chips have billions of transistors. See transistor.

Drs. Bardeen, Shockley and Brattain

This photo of the three inventors was taken in 1947. (Image courtesy of The Computer History Museum.)

EVOLUTION
The first transistors were discrete; each one soldered onto a board to connect to other transistors, resistors and diodes. Since hundreds of transistors were made on the same silicon wafer and cut apart only to be reconnected again, the idea of building them in the required pattern to begin became the goal. In the late 1950s, Jack Kilby of Texas Instruments (TI) figured out how to make capacitors and resistors from the same semiconductor material. Subsequently, Kilby, along with Robert Noyce of Fairchild Semiconductor, created the integrated circuit, a set of interconnected components on a single chip.

Since then, the number of transistors on a single chip has increased exponentially, from half a dozen in the 1960s to billions in the 21st century. As unbelievable as it may seem, today, more than a hundred million transistors fit on the head of a pin! See integrated circuit.

From Tube to Transistors in a Chip

Today, many trillions of transistors would fit inside the first computer tube. The byproduct of miniaturization is speed. The smaller the transistor, the faster it switches. See active area.

LOGIC AND MEMORY
In first- and second-generation computers, internal main memory was made of such materials as tubes filled with liquid mercury, magnetic drums and magnetic cores. As integrated circuits began to flourish in the 1960s, design breakthroughs allowed memories to also be made of semiconductor materials. Thus, logic circuits, the "brains" of the computer, and memory circuits, its internal workspace, were moving along the same miniaturization path.

By the end of the 1970s, it was possible to put a processor, working memory (RAM), permanent memory (ROM), a control unit for handling input and output and a timing clock on the same chip.

Within 25 years, the transistor on a chip grew into the computer on a chip. When the awesome UNIVAC I was introduced in 1951, one could literally open a door and walk inside. Who would have believed the equivalent electronics would some day fit within the head of a pin? No exaggeration (see microcontroller).

To learn how the chip is made, see chip manufacturing. To understand how circuits process data, see Boolean logic.

Transistors to Gates to Circuits

Acting like an on/off switch, the transistor is the main component in a digital circuit. Patterns of transistors make up gates, and patterns of gates make up circuits. This shows a mechanical depiction of a half-adder circuit, which adds one bit to another.

Drilling Down

Although still highly conceptual, this diagram shows more detail of the half-adder circuit above. This depicts the interconnections of only seven transistors, which are implemented in mulitple layers on the chip. Imagine how complicated today's chips really are that contain billions of transistors in an area no larger than a postage stamp. See half-adder.