Article View: comp.sys.ibm.pc
Article #14451Re: CGA & snow
From: karamich
Date: Tue, 04 Nov 1986 23:43
Date: Tue, 04 Nov 1986 23:43
26 lines
1707 bytes
1707 bytes
You'll get snow on a CGA anytime you write ANYWHERE in the CGA
display memory, if you don't check for the vertical retrace. The
snow is caused when you write into the display memory, which isn't
affected by which page is displayed or by which page you're writing
into. For fast screen writes, when you have a lot to write -- like
a screenful, you should first blank the screen, write to the display
memory, then "unblank" the screen. i'm not entirely sure which CGA
register you have to set to what but i've done it before and it works
pretty well.
----
Tom Karamichos
University of Illinois at Urbana-Champaign
Computing Services Office - PC Consulting Dept.
BITNET: karamich@uiucuxc.bitnet
ARPA: karamich@uiucuxc.cso.uiuc.edu
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!lll-crg!rutgers!clyde!cbatt!ihnp4!inuxc!pur-ee!j.cc.purdue.edu!pur-ee!uiucdcs!uiucuxc!karamich From: karamich@uiucuxc.CSO.UIUC.EDU Newsgroups: comp.sys.ibm.pc Subject: Re: CGA & snow Message-ID: <21900186@uiucuxc> Date: Tue, 4-Nov-86 18:43:00 EST Article-I.D.: uiucuxc.21900186 Posted: Tue Nov 4 18:43:00 1986 Date-Received: Sun, 16-Nov-86 07:19:14 EST References: <2193@ecsvax.UUCP> Lines: 26 Nf-ID: #R:ecsvax.UUCP:2193:uiucuxc:21900186:000:1073 Nf-From: uiucuxc.CSO.UIUC.EDU!karamich Nov 4 17:43:00 1986