Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!wuarchive!uunet!pallas!dgl292
From: dgl292@pallas.athenanet.com (Doug Lee)
Newsgroups: comp.sys.ibm.pc.programmer
Subject: PORTABLE Direct Screen access?
Summary: How do you account for various adapters/addresses and screen sizes?
Keywords: screen access, portability
Message-ID: <321@pallas.athenanet.com>
Date: 25 Mar 90 07:49:46 GMT
Reply-To: dgl292@pallas.UUCP (Doug Lee)
Organization: Athenanet, Inc., Springfield, IL
Lines: 22
References:
Organization:


There has been some discussion in this group recently on the subject of
direct screen access.  I am attempting to write a program which, if possible,
must directly access text display memory while remaining portable across a
wide variety of DOS machines.

I am specifically interested in reliable ways to determine the location of
screen memory for a given system and in ways of handling the possibility of
non-80X25 displays.  I will use BIOS calls if necessary, but I am attempting
to avoid the apparent headache of saving/restoring video states (I
initially thought one could simply save/restore the cursor position, but the
only code example I have also directly accesses registers of EGA
(I think) boards where applicable for an unknown purpose).

Information and advice would be MOST appreciated.  If it is easier to do this
using BIOS calls, I would also be interested to know what (if anything) I
must do in addition to saving the cursor position to insure success with
the various adapters in current--and, hopefully, future--use.

Thanks in advance!

Doug Lee  (dgl292@athenanet.com or uunet!pallas!dgl292)