Editing PDP-10 (section)

== Use by CompuServe ==
One of the largest collections of DECsystem-10 architecture systems ever assembled was at [[CompuServe]], which, at its peak, operated over 200 loosely coupled systems in three data centers in [[Columbus, Ohio]]. CompuServe used these systems as 'hosts', providing access to commercial applications, and the CompuServe Information Service. While the first such systems were bought from DEC, when DEC abandoned the PDP-10 architecture in favor of the [[VAX]], CompuServe and other PDP-10 customers began buying [[plug compatible]] computers from Systems Concepts. {{As of|January 2007}}, CompuServe was operating a small number of PDP-10 architecture machines to perform some billing and routing functions.

The main power supplies used in the KL-series machines were so inefficient that CompuServe engineers designed a replacement supply that used about half the energy. CompuServe offered to license the design for its KL supply to DEC for free if DEC would promise that any new KL bought by CompuServe would have the more efficient supply installed. DEC declined the offer.
[[File:MF10-Panel.jpg|thumb|right|250px|MF10 Light Panel with [[LED lamps]]]]

Another modification made to the PDP-10 by CompuServe engineers was replacing the hundreds of incandescent indicator lamps on the KI10 processor cabinet with LED lamp modules. The cost of conversion was easily offset by cost savings in electricity use, reduced heat, and labor needed to replace burned-out lamps. Digital followed this step all over the world. The picture on the right hand side shows the light panel of the MF10 memory which is contemporary with the KI10 CPU. This item is part of a computer museum, and was populated with LEDs in 2008 for demonstration purposes only. There were no similar banks of indicator lamps on KL and KS processors themselves - only on legacy memory and peripheral devices.