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Article #42608Re: EGA 43 line mode. Cursor is missing
From: Tim Larson
Date: Sat, 17 Feb 1990 21:54
Date: Sat, 17 Feb 1990 21:54
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1442 bytes
Sorry to post rather than mail, but my mail to the original poster bounced. This subject may be of general interest anyway. The original post asked why the cursor disappeared after switching the EGA to 43 line mode. On the EGA, cursor emulation is implemented by adding 5 to any Cursor Start or Cursor End value greater than 4 (since the original character matrix was 8 lines high, but the EGA is 14, this provided compatability with old CGA software). However, you are changing the character matrix back to 8 lines high, so simply disabling cursor emulation should work. Change bit 0 of the Video Display Data Area INFO byte (0040:0087) to 1 (leaving other bits unchanged) *before* calling INT 10H function 01H. By the way, the VGA takes the character height into account, so this information is EGA-specific. (Source: "Programmer's Guide to PC & PS/2 Video Systems," Richard Wilton, [Redmond, WA: Microsoft Press], 1987. An excellent book, BTW :)) Cheers! -Tim Larson trl3@psuvm.bitnet
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arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!wuarchive!psuvax1!psuvm!trl3References:
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!wuarchive!psuvax1!psuvm!trl3 From: TRL3@psuvm.psu.edu (Tim Larson) Newsgroups: comp.sys.ibm.pc,alt.msdos.programmer Subject: Re: EGA 43 line mode. Cursor is missing Message-ID: <90048.165401TRL3@psuvm.psu.edu> Date: 17 Feb 90 21:54:01 GMT References: <85@leedat.UUCP> Organization: Penn State University Lines: 23