The Intel 80286 is a 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non-multiplexed address and data buses and also the first with memory management and wide protection abilities. The 80286 used approximately 134,000 transistors in its original nMOS (HMOS) incarnation and, just like the contemporary 80186, it can correctly execute most software written for the earlier Intel 8086 and 8088 processors.
The 8086 is a 16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released. The Intel 8088, released July 1, 1979, is a slightly modified chip with an external 8-bit data bus, and is notable as the processor used in the original IBM PC design.
The Intel 8088 microprocessor is a variant of the Intel 8086. Introduced on June 1, 1979, the 8088 has an eight-bit external data bus instead of the 16-bit bus of the 8086. The 16-bit registers and the one megabyte address range are unchanged, however. In fact, according to the Intel documentation, the 8086 and 8088 have the same execution unit (EU)—only the bus interface unit (BIU) is different. The 8088 was used in the original IBM PC and in IBM PC compatible clones.
The Intel 386, originally released as the 80386 and later renamed i386, was the first x86 32-bit microprocessor designed by Intel. Pre-production samples of the 386 were released to select developers in 1985, while mass production commenced in 1986. The processor was a significant evolution in the x86 architecture, extending a long line of processors that stretched back to the Intel 8008. The 386 was the central processing unit (CPU) of many workstations and high-end personal computers of the time. The 386 began to fall out of public use starting with the release of the i486 processor in 1989, while in embedded systems the 386 remained in widespread use until Intel finally discontinued it in 2007.
The Intel 486, officially named i486 and also known as 80486, is a microprocessor introduced in 1989. It is a higher-performance follow-up to the Intel 386. It represents the fourth generation of binary compatible CPUs following the 8086 of 1978, the Intel 80286 of 1982, and 1985's i386.
The i486SX was a microprocessor originally released by Intel in 1991. It was a modified Intel i486DX microprocessor with its floating-point unit (FPU) disabled. It was intended as a lower-cost CPU for use in low-end systems—selling for US$258—adapting the SX suffix of the earlier i386SX in order to connote a lower-cost option. However, unlike the i386SX, which had a 16-bit external data bus and a 24-bit external address bus, the i486SX was entirely 32-bit. The Intel486 SX-20 CPU can perform up 20 MIPS at 25 MHz while this can also perform 70% faster than the 33 MHz Intel386 DX with external cache.
The Intel 80186, also known as the iAPX 186, or just 186, is a microprocessor and microcontroller introduced in 1982. It was based on the Intel 8086 and, like it, had a 16-bit external data bus multiplexed with a 20-bit address bus. The 80188 variant, with an 8-bit external data bus was also available.
A microprocessor is a computer processor for which the data processing logic and control is included on a single integrated circuit (IC), or a small number of ICs. The microprocessor contains the arithmetic, logic, and control circuitry required to perform the functions of a computer's central processing unit (CPU). The IC is capable of interpreting and executing program instructions and performing arithmetic operations. The microprocessor is a multipurpose, clock-driven, register-based, digital integrated circuit that accepts binary data as input, processes it according to instructions stored in its memory, and provides results as output. Microprocessors contain both combinational logic and sequential digital logic, and operate on numbers and symbols represented in the binary number system.
x86 is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel, based on the 8086 microprocessor and its 8-bit-external-bus variant, the 8088. The 8086 was introduced in 1978 as a fully 16-bit extension of 8-bit Intel's 8080 microprocessor, with memory segmentation as a solution for addressing more memory than can be covered by a plain 16-bit address. The term "x86" came into being because the names of several successors to Intel's 8086 processor end in "86", including the 80186, 80286, 80386 and 80486. Colloquially, their names were "186", "286", "386" and "486".
The Intel 8087, announced in 1980, was the first floating-point coprocessor for the 8086 line of microprocessors. The purpose of the chip was to speed up floating-point arithmetic operations, such as addition, subtraction, multiplication, division, and square root. It also computes transcendental functions such as exponential, logarithmic or trigonometric calculations. The performance enhancements were from approximately 20% to over 500%, depending on the specific application. The 8087 could perform about 50,000 FLOPS using around 2.4 watts.
The Cyrix Cx486SLC is a x86 microprocessor that was developed by Cyrix. It was one of Cyrix's first CPU offerings, released after years of selling math coprocessors that competed with Intel's units and offered better performance at a comparable or lower price. It was announced in March of 1992, and released 2 months later in May, with a price of $119. It was priced competitively against the Intel 486SX, causing Intel to lower the price of their chip from $286 to $119 in just days.
The Cyrix Cx486DLC is an x86 desktop microprocessor developed by Cyrix. It was Cyrix's second CPU offering, released years after selling math coprocessors that competed with Intel's units and offered better performance at a comparable or lower price. It was released in June of 1992, with a price of $119 for computer manufacturers.
x87 is a floating-point-related subset of the x86 architecture instruction set. It originated as an extension of the 8086 instruction set in the form of optional floating-point coprocessors that work in tandem with corresponding x86 CPUs. These microchips have names ending in "87". This is also known as the NPX. Like other extensions to the basic instruction set, x87 instructions are not strictly needed to construct working programs, but provide hardware and microcode implementations of common numerical tasks, allowing these tasks to be performed much faster than corresponding machine code routines can. The x87 instruction set includes instructions for basic floating-point operations such as addition, subtraction and comparison, but also for more complex numerical operations, such as the computation of the tangent function and its inverse, for example.
The Intel 80387SX is the math coprocessor, also called an FPU, for the Intel 80386SX microprocessor. Introduced in 1987, it was used to perform floating-point arithmetic operations directly in hardware. The coprocessor was designed only to work with the 386SX, rather than the standard 386DX. This was because the original 80387 could not communicate with the altered 16 bit data bus of the 386SX, which was modified from the original 386DX's 32 bit data bus. The 387SX uses a 68-pin PLCC socket, just like some variants of the 80286 and the less common 80186 CPU, and was made in speeds ranging from 16 MHz to 33 MHz, matching the clock speed range of the Intel manufactured 386SX. Some chips like the IIT 3C87SX could get up to 40 MHz, matching the clock speeds of the fastest 386SX CPUs.
The maximum random access memory (RAM) installed in any computer system is limited by hardware, software and economic factors. The hardware may have a limited number of address bus bits, limited by the processor package or design of the system. Some of the address space may be shared between RAM, peripherals, and read-only memory. In the case of a microcontroller with no external RAM, the size of the RAM array is limited by the size of the integrated circuit die. In a packaged system, only enough RAM may be provided for the system's required functions, with no provision for addition of memory after manufacture.
Intel 8237 is a direct memory access (DMA) controller, a part of the MCS 85 microprocessor family. It enables data transfer between memory and the I/O with reduced load on the system's main processor by providing the memory with control signals and memory address information during the DMA transfer.
The Intel 8231 and 8232 were early designs of floating-point maths coprocessors (FPUs), marketed for use with their i8080 line of primary CPUs. They were licensed versions of AMD's Am9511 and Am9512 FPUs, from 1977 and 1979, themselves claimed by AMD as the world's first single-chip FPU solutions.
