[net.micro.pc] Reverse Video on the IBM PC

bamford@ihuxw.UUCP (Harold Bamford) (04/12/85)

I have been working on a way to get reverse video on my IBM PC.  I wrote
an intercept function for INT 10 and when functions 6 (scroll up), 7
(scroll down), or 9 (Write Attribute/Char) were being called, I reverse
the foreground and background bits.  Simple so far, but it only
partially works:  New characters written to the screen are indeed in
reverse video, and a "cls" command to DOS puts the entire screen in
reverse video.

However --

When the screen scrolls up, as when "type"ing a large file or "dir" on a
large directory, the new lines are not reverse video -- they are normal
video except where a character is printed.

My suspicion is that the "write teletype" function (14) is not
performing as advertised.  To quote the comment preceding the assembly
language code: "...If the row value leaves the field, the cursor is placed
on the last row, first column, and the entire screen is scrolled up one
line.  When the screen is scrolled up, the attribute for filling the
newly blanked line is read from the cursor position on the previous line
before the scroll..."  I believe that the scroll function works as it is
used for the "cls" command.

Does anybody have any suggestions as to how to fix this problem?  Be
assured that if there is sufficient interest in the "fixed" program,
that it will be posted to net.sources with proper acknowledgements.

As always, thanks in advance...

				Harold

-- 

				Harold Bamford
				AT&T Bell Labs
				Naperville, Ill
				(cornet) 8-367-5744
				(312) 979-5744	(work)