Controller in Computer

Memory controller: This is the logic circuit that controls the reading and writing of data to and from system memory (RAM). Other devices on the PC wishing to access memory must interface with the memory controller. This feature also usually includes error handling to provide for parity checking and ECC (error-correcting code) for every memory word.

EIDE controller: Nearly all mid- to upper-range motherboards now include at least one EIDE connector for hard disks, floppy disks, CD-ROMs, DVDs, or other types of internal storage drives. The EIDE controller typically supports devices with ISA, ATA, and perhaps an ATA-33 or Ultra-DMA (UDMA) interface.

Real-time clock (RTC): This clock holds the date and time on your PC; this is the date and time that is displayed to you on the monitor and is used to date-stamp file activities. This should not be confused with the system clock that provides the timing signal for the processor and other devices.

DMA (Direct Memory Access) controllers: The DMA controller manages the seven DMA channels available for use by ISA/ATA devices on most PCs. DMA channels are used by certain devices, such as floppy disk drives, sound cards, SCSI adapters, and some network adapters, to move data into memory
without the assistance of the CPU.

IrDA controller: IrDA (Infrared Data Association) is international an organization that has created the standards for short-range, line-of-sight, point-to-point infrared devices, such as a keyboard, mouse, and network adapters. The IrDA port on your system is that small red window on the front or side of the notebook and some desktop computers.

Keyboard controller: A chipset may include the keyboard controller, and many of the newer ones do. The keyboard controller is the interface between the keyboard and the processor. See the previous section for more information on this device.

PS/2 mouse controller: When IBM introduced the PS/2 system, the controller for the mouse was included in the keyboard controller. This design has persisted and usually wherever the keyboard controller is, so is the PS/2 mouse controller. This device provides the interface between the PS/2 mouse and the processor.

Secondary (Level 2, or L2) cache controller: Secondary (L2) cache is located on the motherboard, a daughterboard, or as on the Pentium Pro, in the processor package, and caches the primary memory (RAM), the hard
disk, and the CD-ROM drives. The secondary cache controller controls the movement of data to and from the L2 cache and the processor.