Coprocessor

A coprocessor is an additional microprocessor, which supports the main processor ( CPU) in his work. In particular, a GPU can be viewed as a coprocessor.

Another example is a math coprocessor (often floating point unit ), the calculations of floating point takes over for the main processor. Modern processors do not need any more coprocessor, as they have integrated a floating point unit. One of the first arithmetic co-processors was the AMD AM9511, has been raised as a peripheral block of the microprocessor.

Well-known members of this genus were the floating point math co-processors Intel 8087, Intel 80287 and Intel 80387, as they had to be purchased separately as an accessory to their time. The accompanying chips had no built-in floating point unit, so that floating-point calculations had to be performed by complex software routines, which was significantly slower than floating-point calculations in hardware. Many programs have therefore been developed for fixed-point arithmetic, as these by the Arithmetic Logic Unit (ALU ) can be efficiently implemented. With the i486 x86 CPUs are equipped with a built-in floating point unit, so that the coprocessor was unnecessary. In the stripped-down low-cost version 486SX floating point unit was indeed on the present, but disabled and non-functional.

Coprocessors for other systems are Motorola 68881 or 68882nd Historically relevant manufacturers are further Cyrix, IIT, and Weitek.

As well as co-processors processors for digital signal processing ( DSP ), such as the Motorola 56001 or the AT & T 3210 apply. Recently, the PhysX co-processor of Ageia made ​​for fast calculation of three-dimensional physical effects to be attentive.

Coprocessors in the I / O processing

Coprocessors are also used for I / O processing. An I / O processor (English I / O processor, IOP; occasionally I / O processor ) is a coprocessor that supports the main central processor is to process input and output operations. For this purpose, data from peripherals like printer, scanner, monitor, mouse, or from storage media such as magnetic tapes, floppy disks or hard disks are read and written to the memory ( = direct memory access (DMA ) ). Using I / O processors is also possible to process the data read out. Examples include the Intel processors Intel 8089, IOP 341/342, MCS -48 or UPI -41 (Universal Peripheral Interface) as well as the Apple M7, the data from motion sensors of the Apple iPhone 5s irrespective of a main CPU, processed and caches and therefore affects low-power ending.