Short for tagged command queuing, a method of processing requests from a host device to a hard drive that is storing the data requested. TCQ was first introduced with the SCSI-2 standard as a way to allow hard drives to accept multiple concurrent commands from a host PC. When commands arrive at the drive’s buffer, they are tagged with an identifier and then reordered by the drive��s microprocessor to minimize the distance the drive’s read head needs to move laterally along the platter looking for data. For example, if a command is looking for data in one section of the drive and a following queued command is looking for data in a neighboring area, the SCSI host adapter can reorder the commands to make the two occur sequentially. This is a different system than SCSI-1 or IDE/ATA, which will allow only a single command to be outstanding at a time to any device and processes requests serially.
Tagged command queuing also is called command queuing and reordering.
Short for Time Division Multiplexing, a type of multiplexing that combines data streams by assigning each stream a different time slot in a set. TDM repeatedly transmits a fixed sequence of time slots over a single transmission channel. Within T-Carrier systems, such as T-1 and T-3, TDM combines Pulse Code Modulated (PCM)streams created for each […]
Short for Time Division Multiple Access, a technology for delivering digital wireless service using time-division multiplexing (TDM). TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels. TDMA is used by the GSM digital cellular system.
Time Domain Reflectometry is used to pinpoint flaws and problems in underground and aerial wire, cabling, and fiber optics. Time Domain Reflectometers send a signal down the conductor and measure the time it takes for the signal — or part of the signal — to return. The signal’s reflection begins at the flaw point. Once […]
Short for telecommunications equipment manufacturer.
- TCP-Friendly Rate Control
TCP-Friendly Rate Control (TFRC) is a congestion control mechanism designed for unicast flows operating in an Internet environment and competing with TCP traffic. It is designed for applications that use a fixed packet size, and vary their sending rate in packets per second in response to congestion. TFRC is a receiver-based mechanism, with the calculation […]