[comp.os.minix] Speed Up CGA Screen Output by a Factor of 2

zemon@felix.UUCP (Art Zemon) (05/19/87)

By commenting out the code in vid_copy (in klib88.s) which waits for
vertical retrace, I sped up screen output immensely.  The real time for

	$ time cat wini.c

decreased from 45 seconds to 24 seconds.  This change is reasonable if
you have a "smart" CGA card (like the Zenith) which can accept updates
to video RAM at all times.  The change involved commenting out the code
at labels vid.1, vid.2, and vid.3 (five lines in all).  You must also
change the reference to vid.1 about four lines further up to vid.4.
Note that the distributed code and the book differ here.  My references
are to the code but the same region of code is in the book lines
1715-1722.

Try the change.  If your display still looks good, you win and have a
much faster console.  If you get a lot of snow on the screen, back out
the change.
-- 
	-- Art Zemon
	   FileNet Corporation
	   Costa Mesa, California
	   ...!hplabs!felix!zemon