Date of this Version
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.
Gaylord Holder, "A General Device Driver for Ultrix or Leave the Driver to /dev/bus", . February 1989.
Date Posted: 06 December 2007