Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!amdahl!rtech!bobm@rtech.UUCP
From: bobm@rtech.UUCP (Bob McQueer)
Newsgroups: comp.graphics
Subject: Re: 4014 stuff
Message-ID: <2007@rtech.UUCP>
Date: 24 Apr 88 22:18:17 GMT
References: <206300001@prism>
Sender: news@rtech.UUCP
Lines: 17

From article <206300001@prism>, by jms@prism.TMC.COM:
> 
> 	I'm pretty sure that there is no way to remove what is displayed.
> This is the big disadvantage of storage tubes.  Refreshing the display
> is done by clearing the screen......

I haven't seen a real storage tube for years, but I DO recall that
there is a way to do a selective erase, essentially making your "pen"
an "eraser" and allowing you to retrace what you've already drawn.  I
remember it as being one of about six modes in the Tek manual represented
by circles in a state diagram showing the control sequences required
to get from mode to mode.  I don't recall the sequence, and no longer
have the appropriate documentation at my fingertips.  Another interesting
mode the storage tubes could be put into was a "write-through" mode in
which your vectors would fade out in a fraction of a second.  It was
intended for the case where you had a dedicated machine to support
refreshing the display continually.  These added modes may not be
present on all 40xx devices - I remember it specifically from 4014's.