Re: Anybody with an oscilloscope as an Apple II display?

["Michael J. Mahon" <mjmahon@aol.com>]

nyder wrote:
> I have an Vacuum Tube Tektronix 585a, dual traces.
>
> Would it work better for this then a more modern one?

Any CRT-based scope will work--newer LCD models, not so much.

> I've always been interested in using an oscilloscope in this manner,
> since I read thats how they got the first game, space wars (forget
> it's name) displaying.

Well, actually, it was a vector display, not really an oscilloscope,
though the first vector display no doubt *was* an oscilloscope in
X-Y mode.

Ironically, the first computer graphical displays were raster-
scanned, and connected to the address bus of the machines--because
they were "slave" tubes slaved to the Williams Tube CRT memory
systems!  Of course, for reliability only about 32x32 points were
on a tube.

Since all address references were shown (in addition to the regular
refresh scans) the intensity profile of code and data references was
always visible.  Many machines put a slave tube on the operator's
console so they could observe the operation of the machine and
quickly detect anomalies.

> Of course, i'm sort of scared to turn it on, since I don't want to
> lose any vacuum tubes.  It was working when i got it, so it should
> still be working.

As long as it has been operated within the last few years for an
hour or so, you should have no problems with de-formed electrolytic
capacitors.  It should be safe to operate.

The tube life on Tektronix scopes was pretty good, since they
used very conservative designs.

-michael

NadaPong: Network game demo for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

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