Microprocessor chips (MPU) are silicon devices that serve as the central processing unit (CPU) in computers. They contain thousands of electronic components and use a collection of machine instructions to perform mathematical operations and move data from one memory location to another. Microprocessors contain an address bus that sends addresses to memory, read and write lines, and a data bus that can send data to memory or receive data from memory. They also include a clock line that enables a clock pulse to sequence the processor and a reset line that resets the program counter and restarts execution. Basic microprocessor chip components include one or more arithmetic logic units (ALU) and shift registers. There are two system architectures for microprocessor chips. Devices that use a reduced instruction set computer (RISC) design process a few simple instructions instead of many complex ones in order to speed operations. By contrast, devices that use a complex instruction set computer (CISC) design provide variable length instructions, multiple addressing forms, and contain only a small number of general-purpose registers.
Input/output (I/O) ports and interfaces are connections that provide a data path between microprocessor chips (MPU) and external devices such as keyboards, displays, and readers. The number of I/O ports is equal to the number of input, output, and general-purpose ports (lines) combined. Communication controllers manage data inputs and outputs. They also convert data outputs for transmission over communication lines and perform all of the necessary control functions, error checking, and synchronization. Interfaces for microprocessor chips include transport control protocol/internet protocol (TCP/IP), serial peripheral interface (SPI), inter-IC (I2C) bus, infrared data association (IrDA), synchronous data link control (SDLC), high-level data link control (HDLC), and pulse width modulation (PWM). Microprocessor chips (MPU) that use system management bus (SMBus), control area network bus (CANbus), and universal serial bus (USB) ports are also available.
Important specifications to consider when selecting microprocessor chips (MPU) include data bus, microprocessor family, supply voltage, clock speed, random access memory (RAM), power dissipation, and operating temperature. Most microprocessor chips are available with an 8-bit, 16-bit, 24-bit, 32-bit, 64-bit, 128-bit, or 256-bit data bus. Products from many proprietary microprocessor families are commonly available. Supply voltages range from - 5 V to 5 V and include intermediate voltages such as - 4.5 V, - 3.3 V, - 3 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3 V, 3.3 V, and 3.6 V. Clock speed, the frequency that determines how fast devices connected to the system bus operate, is generally expressed in megahertz (MHz). RAM is usually expressed in kilobytes (kB) or megabytes (MB). Power dissipation, the device's total power consumption, is generally expressed in watts (W) or milliwatts (mW). Operating temperature is a full-required range.
Microprocessor chips (MPU) are available in a variety of integrated circuit (IC) package types and with different numbers of pins. Basic IC package types include ball grid array (BGA), quad flat package (QFP), single in-line package (SIP), and dual in-line package (DIP). Many packaging variants are available. For example, BGA variants include plastic-ball grid array (PBGA) and tape-ball grid array (TBGA). Fine-pitch land grid array (FLGA) packages are also common. QFP variants include low-profile quad flat package (LQFP) and thin quad flat package (TQFP). DIPs are available in either ceramic (CDIP) or plastic (PDIP). Other IC package types for microprocessor chips (MPU) include small outline package (SOP), thin small outline package (TSOP), shrink small outline package (SSOP), shrink zigzag inline package (SZIP), and thin very small outline package (TVSOP). Small outline J-lead (SOJ), plastic leaded chip carrier (PLCC), and leadless ceramic chip carrier (LCCC) packages are also available.