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 -♦-