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]

References

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