Device control register

In computing, a device control register is a hardware register that controls some computer hardware device, for example a peripheral or an expansion card.

Specific technologies use this terminology with a narrower meaning:

  • The ISA PNP specification divides the registers of a device in two categories: control registers and configuration registers. One of the device control registers defined by ISA PNP is (for example) the Activate register, which turns the card on or off.[1]
  • The Device Control Register is also the name of a specific register in the PCI Express architecture. It has fields that (among other things) control what is the maximum read request size (in bytes) that the device can make.[2]
  • Device Control Register (DCR) is also the name of an IBM proprietary bus. Its stated design goal is to "transfer data between a DCR master, typically a CPU’s general purpose registers, and the DCR slave logic’s device control registers".[3] For example, the IBM MultiProcessor Interrupt Controller (MPIC) is connected up to four processors via a shared DCR bus, and in turn the MPIC handles up to 128 interrupt sources.[4]
  1. ^ Tom Shanley (1995). Plug and Play System Architecture. Addison-Wesley Professional. p. 156. ISBN 978-0-201-41013-6.
  2. ^ Ravi Budruk (2004). PCI Express System Architecture. Addison-Wesley Professional. p. 906. ISBN 978-0-321-15630-3.
  3. ^ Device Control Register Bus 3.5 Architecture Specifications
  4. ^ IBM Multiprocessor Interrupt Controller. Data Book