> er,not quite. If the phosphor was long persistance every sweep would
> remain on the screen. There is some sort of mesh inside the tube which
> can preserve the scan when energised. Gradually the electrons leak away
> and the trace fades. When storage mode is de-energised, the scope
> reverts to normal display.

er, it does. Well, it can. You can tell the scope not to erase between
sweeps and build up an envelope.
Usually you'd have it erased between sweeps (which means several seconds
betwwen triggers) or set the persistence to low.
My understanding was that it was the phosphor, but I could be wrong. I
recall someone (Iwatsu, perhaps) came up with some sort of hybrid. It had a
tube that worked like an analog scope but they could read the grid/phosphor
back. That was digitised with slower A/D's and then put back up on the
screen.
It may be myth, but it sounds like a good idea. This was back in the days
when DSOs were only a few MHz.

Steve.

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  Very funny Scotty.  Now beam down my clothes.
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Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680                email: steveb@kcbbs.gen.nz
New Lynn, Auckland           ph  +64 9 820-2221
New Zealand                  fax +64 9 820-1929
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