Design Features: September 28, 1995

Cover Story
Distributed operating systems combine multiple processors into a single machine	Distributed operating systems let you fuse a collection of processors into one virtual machine that is independent of the system architecture. System performance, however, will rely heavily on how those processors are connected. -- Richard A Quinnell, Technical Editor
Design Features The hottest new technologies and the latest design techniques to help you work efficiently and effectively.
Vectorless test: process development made simple	New techniques for finding process faults in surface-mount boards speed up and simplify test development. The techniques don't do away with the need to design boards for testability, however. --Dan Strassberg, Senior Technical Editor
Supervisory ICs establish system boundaries	Although they don't have the glamour of CPUs, memories, or sophisticated peripheral ICs, supervisory ICs perform unseen yet critical tasks in reset, memory protection, and watchdog functions. You have to choose among a wide variety of ICs and levels of functional integration, and you must decide what level of confidence you need in your watchdog operation. --Bill Schweber, Technical Editor
RS-232C/422/485 line isolation solves more than fault problems	Galvanic, or electrical, isolation is a well-established technique for noise reduction and works best in computer and industrial systems in which noise can seriously affect data transfer. Isolation removes ground-loop currents and their associated noise voltages from data lines. --Ron Clark and Bob Underwood, Maxim Integrated Products
Design innovations provide for voltage-tunable, state-variable active filters for megahertz ranges	A new generation of wideband amplifiers and multipliers allows you to build state-variable active filters that operate beyond the kilohertz region into the megahertz region. Using these devices and appropriate design techniques provides a very linear tuning characteristic. --Chris Siu, Elantec Corp