Xref: utzoo comp.os.vms:3831 comp.editors:48
Path: utzoo!mnetor!uunet!husc6!hao!ames!ucbcad!ucbvax!decvax!decwrl!pyramid!voder!blia!ted
From: ted@blia.BLI.COM (Ted Marshall)
Newsgroups: comp.os.vms,comp.editors
Subject: Re: VT100 confused by TPU
Message-ID: <3778@blia.BLI.COM>
Date: 22 Dec 87 19:02:16 GMT
References: <2080@charon.unm.edu>
Distribution: na
Organization: Britton Lee, Los Gatos, CA
Lines: 26
Keywords: VMS TPU vt100 firmware confusion
Summary: Firmware bug in early VT-100's

In article <2080@charon.unm.edu>, sdowdy@charon.unm.edu (Stephen Dowdy) writes:
> I am designing a minimal pager mechanism in TPU and have come across
> a problem.  The pager, so far, works fine on all DEC crts that i have
> tried, except for VT100's marked VT100-AA.  If i page up and down
> several times, the vt100 gets extremely confused about what its
> scrolling region is and where to put the next line of text.  This
> problem persists even upon exiting TPU.  Doing something like
> $ DIR/COLUMN=1	! or any command with plain text output
> cause the screen output to jump from one line to another without
> much relation to screen order.

My memory is somewhat fuzzy, but since no-one else has said anything, I will
see what I can dredge-up.

As I recall, there was a firmware bug in at least some VT-100's. I think it
had to do with scrolling regions under soft-scroll. I remember that it could
be pushed far enough that the terminal did a full reset.

I don't know if this was fixed in later versions of the VT-100 family (I assume
so) or what models/serial-numbers had the problem. However, I do remember that
turning off soft-scroll mode fixed it. Try that.

-- 
Ted Marshall       ...!ucbvax!mtxinu!blia!ted <or> mtxinu!blia!ted@Berkeley.EDU
Britton Lee, Inc., 14600 Winchester Blvd, Los Gatos, Ca 95030     (408)378-7000
The opinions expressed above are those of the poster and not his employer.