We propose to build hardware and software
to enable a network of workstations (NOW) to act as a single
large-scale computer. Because of volume production, commercial
workstations today offer much better price/performance than the
individual nodes of MPPs; in addition, switch-based networks 
such as ATM will provide cheap, high-bandwidth communication.
This price/performance advantage is increased if the NOW can be 
used for both the tasks traditionally run on workstations and 
large programs. We hope to demonstrate a practical 100 processor 
system in the next few years that delivers at the same time 
(1) better cost-performance for parallel applications than a 
massively parallel processing architecture (MPP) and (2) better 
performance for sequential applications than an individual 
workstation (by using more of the resources of the network). 
If projects like NOW are successful, they have the potential to 
redefine the high-end of the computing industry.
	To realize the potential of NOWs, we need to move two 
MPP technologies into the workstation community: low latency 
networking and global system software that treats a collection 
of processors, memory, and disks as if they were a single 
machine.  Our approach is to leverage off-the-shelf technology 
as much as possible -- workstation hardware, standard 
workstation operating systems on each node, and local area 
network ATM switches. To this, we will add communications 
protocol software and a global system layer that together 
provide low overhead communication, a single view of operating 
system services across the cluster, parallel file I/O, and 
robustness to individual node failures.  We will demonstrate our 
results by using our system for the everyday computing needs, 
both sequential and parallel.