Light pens?

[Peter C. Wallace]

On Fri, 18 Mar 2005, Eric Smith wrote:

> Tony wrote:
>> I can tell you that although the MDA card has a light pen connector, the
>> light pen certainly doesn't work on the 5151 monitor (far too long a
>> persistance).
>
> Long persistence phospor doesn't preclude the use of a light pen, it
> just introduces some limitations on the usage model.  The DEC Type 30
> and 340 displays as used on the PDP-1 through PDP-10 use a P7 phosphor
> which has very high persistence, yet light pens were commonly used with
> them.
>
> Eric
>

You can cheat with P7 and other double layer phosphors by using a blue filter 
as they have a medium or short persistance blue phosphor and a very long 
persistance yellow or orange phosphor.

Peter Wallace