Fitting the missing light pen strobe on early beebs

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Fitting the missing light pen strobe on early beebs

Postby tricky » Sat Aug 19, 2017 11:57 am

I have been informed that some of the early beebs didn't have the LPSTB (Light Pen Strobe) fitted, which I guess means that they don't have the track on the circuit board.

Looking at the circuit diagram, it looks like the Analogue 15 pin connector pin 9 (the one on the same end as +5v) LPSTB connects directly to pin 19 CB2 of IC3 the System 6522 VIA, I can't even see any pull-up or pull-down resistors.

Can anyone confirm that this track was missing on any beebs?

Can anyone confirm that jumping the two pins with a simple wire would be equivalent to the normal beeb connection?

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