Device control register

Device control register

A device control register (DCR) is a register that resides in an element of a System-on-a-chip (e.g. a memory unit, a DMA controller, other bus controller, a timer etc.) and allows to configure, control and probe this element.

Typically, a microprocessor or a processor core is the entity that initiates these tasks, thus a master-slave configuration is created. Communications between the master (the processor) and the slaves (other on-chip elements or peripheral devices) are carried out using a specialized bus with its own address space and means of access.

Because DCRs exist architecturally and physically outside the main processor core, their semantics is independent of the processor functions. Thus they are not specified by the processor programming manuals, which typically define the DCR space, but make no claims regarding which facility or device corresponds to which part of the space.

DCRs are typically accessed through the use of privileged instructions.

Examples:

  • The embedded PowerPC chips have a special DCR Bus which allows the processor to access other devices on the bus, bypassing standard memory and bus controllers. The data transfers to DCRs are initiated using the special mtdcr (move to DCR) and mfdcr (move from DCR) instructions.
  • The compute cores of Blue Gene supercomputer expose DCRs for access to JTAG functions [1].

References

  1. ^ Blue Gene/L compute chip: Control, test, and bring-up infrastructure

External links



Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Control register — A control register is a processor register which changes or controls the general behavior of a CPU or other digital device. Common tasks performed by control registers include interrupt control, switching the addressing mode, paging control, and… …   Wikipedia

  • Device driver — Operating systems Common features …   Wikipedia

  • Device register — A Device Register is the view any device presents to a programmer. Each programmable bit in the device is presented with a logical address and it appears as a part of a byte in the device registers. Then programming of these bits can be achieved… …   Wikipedia

  • control — [kən trōl′] vt. controlled, controlling [ME countrollen < Anglo Fr contreroller < Fr contrerole < ML contrarotulus, a counter, register < L contra, against + rotulus: see ROLL] 1. Obs. to check or verify (payments, accounts, etc.) by… …   English World dictionary

  • Control/Status Register — Control and Status Register (CSR) is a register in many central processing units that are used as storage devices for information about instructions received from machines. The device is generally placed in the register address 0 or 1 in CPUs [1] …   Wikipedia

  • Device driver synthesis and verification — The device driver is a program which allows the software or higher level computer programs to interact with a hardware device. These software components act as a link between the devices and the operating systems, communicating with each of these …   Wikipedia

  • Control unit — A control unit in general is a central (or sometimes distributed but clearly distinguishable) part of the machinery that controls its operation, provided that a piece of machinery is complex and organized enough to contain any such unit. One… …   Wikipedia

  • Register machine — In mathematical logic and theoretical computer science a register machine is a generic class of abstract machines used in a manner similar to a Turing machine. All the models are Turing equivalent. Contents 1 Overview 2 Formal definition 3 …   Wikipedia

  • control — controllable, adj., n. controllability, controllableness, n. controllably, adv. controlless, adj. controllingly, adv. /keuhn trohl /, v., controlled, controlling, n. v.t. 1. to exercise restraint or direction over; dominate; command …   Universalium

  • register —    A device that accepts and stores information, usually a called number, then uses that information to control the switch …   IT glossary of terms, acronyms and abbreviations

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”