Direct Memory Access. Part II

All parameters that enable to allocate channels of direct memory access, as well as all parameters of allocation of interruptions, are located in a section “PNP/PCI Configuration BIOS”.

Use the parameter “DMA n Assigned to” (DMA Resources, DMA Channel n) for manual allocation of DMA-channels, where n – a number of assigned channel (from0 to 7 inclusively). The descriptions of device types that must be connected to the particular channels are used as the values of this parameter.

  • Legacy ISA (ISA/EISA) – a channel for ISA-devices that do not support Plug and Play mechanism. A channel for such devices is set manually using a switcher.
  • PCI/ISA PnP (PnP) – a channel for PCI and ISA-devices that support the Plug and Play mechanism.

Except the above parameter, BIOS may use an identical parameter “DMA n Type”, where n – a number of assigned channel (from 0 to 7 inclusively). This parameter may have the following four values: Normal ISA – ISA-device that supports the Plug and Play mechanism; PC/PCI – PCI-device that supports the Plug and Play mechanism; Distributed – a device that does not support the Plug and Play mechanism; LPC DMA – a device connected via LPC-bus.