It's *probably* a multichannel analyzer (MCA), not an oscilliscope. MCA's look at pulse heights and generate real-time cumulative histograms of pulse height on the screen. Tracor Northern is one of the more prolific manufacturers of MCA's. I once got to look at a MCA from the late 1940's, and it was fascinating: the input pulse was amplified, then fed to a solenoid that kicked a ball bearing up in a ballistic trajectory. There were bins that accumulated ball bearings according to how hard they'd been kicked. Fascinating machine! Of course, modern MCA's use computers to do the counting :-). -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927