Computer Terms

I/O Bus -- an I/O Bus is actually a logical interface between two components in a system, and these two components can either be a processor and specific memory, calculation or transformational logic routine embedded in firmware, or can also be peer-to-peer components, depending on the logic approach as defined by the I/O Bus definition. The Small Computer Systems Interface (SCSI) bus is actually used for managing multiple system, storage and peripheral components in conjunction with one another. An I/O Bus is a critical element in any computer or network system.

Interrupts -- These are unforeseen and often random events that one system component relies on to gain access to resources needed for completing a request. Interrupts are often used in pre-emptive multitasking-based operating system as the many threads from applications an microprocessor is managing need to gain access to both memory and processor power, hence the development of an interrupt for resources.

Memory-Mapped I/O -- This is memory in a system that has specifically been designed for programmers to quickly gain access to specific memory locations in the definition of their programs. Memory-mapped I/O increases the performance of applications significantly as a result.

Direct Memory Access (DMA) -- Designed for higher efficiency in programming tasks and the development of faster access speeds, DMA is memory that by definition is mapped directly from the microprocessor to the memory locations themselves, alleviating the need to go through specific programming and intermediary steps.

Seek time -- the amount of time required for a storage device to find a specific requested record or element of data. Seek times in disk drives are significantly different that DMA for example.

Rotational latency -- One of the three measures of performance for disk drives, rotational latency, seek time, and transfer time are all combined to quantify total disk drive performance. Rotational latency is the time required for the disk drives' electronics to place the correct head, sector and track information below the read/write head for accessing.

Transfer time -- in the context of disk drive performance, transfer time is the time needed to read or write data to the hard disk drives' surface, often organized in head, sector and track format.