Path: utzoo!attcan!uunet!lll-winken!sun-barr!apple!jerryg
From: jerryg@Apple.COM (Jerry Godes)
Newsgroups: comp.sys.mac.comm
Subject: Re: MacTerminal 3.0
Message-ID: <10970@goofy.Apple.COM>
Date: 27 Oct 90 00:17:39 GMT
References: <4231@lib.tmc.edu> <18@uarthur.UUCP> <1990Oct26.160453.6496@silvlis.com>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 36

In article <1990Oct26.160453.6496@silvlis.com> jimb@silvlis.com (Jim Budler) writes:
>In article <18@uarthur.UUCP> rpcfod@uarthur.UUCP (Robert Patt-Corner) writes:
>
>>There's another known bug having to do with screen drawing -- try this:
>
>>a.	Run the VAX TPU editor (Edit/TPU) on a file
>>b.	Mark and cut a passage
>>c.	Move your cursor somewhere
>>d.	Paste the passage
>>e.	Hit the UpArrow
>
>>Wheee.  Watch a big illusory blank area open in your screen.
>
>This is not unique to MacTerminal by any means. I've encountered it
>with other terminal programs also.
>
>Does anyone know what feature of vt emulation causes it?
>
Yup - 
I just tracked down the problem for the VT100 and VT320 tools.  The problem
has to do with TPU's bizarre method of moving the cursor.  When the user does
a cut, TPU sets a scroll margin and then scrolls the cut lines off of the
display.  However, when finished with the cut, it does not reset the margin.
When you press the up arrow, normally, TPU generates a Reverse Index.
However, when it reaches the top of the scroll margin, it generates a direct
cursor position command.  Once above the margin, it reverts to generating
Reverse Indeces.  The problem with the tool is the handling the RI when above
the scroll margin.

Of course, I don't have an easy solution (other than generating a refresh
after each cut).

What other Terminal emulators exhibit this behavior? (Just for my own
interest). 

Jerry