CPU Support Chips
Carries out tasks on behalf of the CPU.
Examples:
- Direct Memory Access controllers
- Disk controllers
- Real-Time Clock
- Display controllers
- Interrupt controllers
- Communication controllers
DMA controllers
Provides a way of bypassing the CPU when transferring data between memory and Input/Output (IO) devices. Resides between memory and CPU.
Disk controllers
When reading/writing to/from a disk the CPU will create a buffer (special memory area) containing the sector address and the data to be written or read. Then the CPU informs the controller about the location of the buffer. The controller then transfers the content of the buffer directly from memory to the disk sector.
Examples:
- Floppy Disk Controller
- ATA Controller
Real-Time Clocks
Used to keep track of time of the day. Usually backed-up by an extra power source such as a Li battery. Used to store some of the configuration information such as CMOS setup memory.
Display controllers
Used to generate images and text that you see on the displaying device on behalf of the CPU. The actual image (which is binary data) is generated in its memory called “refresh buffer”, then passed to video controller to be displayed.
Video controllers
Used to display the image on monitors. Classified based on their video processor and video memory.
Some video standards are:
- Video Graphics Array - minimum resolution: 320x240 in 256 colors or 640x480 in 16 colors
- Super VGA - supports resolution up to 800x600
- Video Electronics Standards Association SVGA - was developed to standardize SVGA. Also includes a video standard for connecting high-speed adaptors directly to the processor bus.