A General Device Driver for Ultrix or Leave the Driver to /dev/bus

New hardware is the bane and the boon of the research laboratory: the boon because it brings new power, new capabilities, and new solutions; the bane because it means someone has to sit down and write the interface code for the board. /dev/bus attempts to simplify the process on the MicroVAX IIs running Ultrix 2.0 by allowing user processes direct access to the board's control status registers and Q-Bus memory. Unlike similar drivers for Suns, RTs and Masscomp, /dev/bus provides a means of establishing a user function as an interrupt handler. The delays and variability of the interrupt delivery are analyzed. Problems with the implementation are also described.