Installable Device Drivers

 An installable device driver lets you create a standard interface between

 DOS and an otherwise unsupported hardware device.  TECH Help! covers the

 following topics:



   Device Driver Basics ........  general introduction to device drivers



   Device Header Layout ........  data structure a the start of a driver

   Device Attribute ............  bit flags that define a device



   Device Requests .............  services a device driver must perform

   Device Request Header .......  layout of first part of a request packet

   Device Driver Errors ........  error codes a driver returns to DOS

   Device Status Word ..........  device status bit flags returned to DOS

   BPB: BIOS Parameter Block ...  a structure used by block devices



   IOCTL Functions .............  these communicate with a driver directly



   Mouse Support ...............  INT 33H fns are installed as a driver

   Expanded Memory Specification  EMM Fns are installed as a device driver

   DoubleSpace .................  disk-compression installed as a driver

   MRCI API ....................  disk-compression installed as a driver

   INT 2fH .....................  DOS extensions installed as drivers



See Also: CONFIG.SYS

          DOS Functions

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