Adaptec PCM-3420, PC/104 manual Devicedriver, Differential, Dma Direct Memory Access

C

D

DEVICEDRIVER

A software program that enables a PC to communicate with peripheral devices such as fixed disk drives and CD-ROM drives. Each kind of device requires a different driver. Device driver programs are stored on a PC’s fixed disk and are loaded into memory at boot time.

DIFFERENTIAL

A term referring to the electrical characteristics of the signals used on the SCSI bus interface. Differential signals occupy two conductors with a positive (+) and negative (-) polarity compo- nent of the signal. This minimizes the effect of common mode signal noise and allow the SCSI bus to operate reliably over greater distances at a higher speed.

DMA (DIRECT MEMORY ACCESS)

A mechanism that allows hardware control of the transfer of streams of data to or from the main memory of a computing system. The mechanism may require setup by the host software. After initialization, it automatically sequences the required data transfer and provides the necessary address information.

4 4 PCM-3420 User's Manual