Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!att!cbnewsh!rkl From: rkl@cbnewsh.att.com (kevin.laux) Newsgroups: comp.os.msdos.programmer Subject: Re: Dual Monitor Switching Message-ID: <1991Mar13.145206.4281@cbnewsh.att.com> Date: 13 Mar 91 14:52:06 GMT References: <1991Mar11.172914.4450@engin.umich.edu> <6150@amc-gw.amc.com> Distribution: na Organization: AT&T Bell Laboratories Lines: 33 In article <6150@amc-gw.amc.com>, jwbirdsa@amc-gw.amc.com (James Birdsall) writes: > In article <1991Mar12.140842.63@cbnewsh.att.com> rkl@cbnewsh.att.com (kevin.laux) writes: > >In article <18203@milton.u.washington.edu>, roger@wrq.com (Roger Fulton) writes: > >> In addition to setting the video mode, > >> you need to also update the equipment flag at 0040:0010 > >> appropriately: xx10xxxx for color, xx11xxxx for mono > >> (where 'x' means leave it alone). Also, you should account > >> for the fact that color systems have a different maximum > >> cursor line count than mono systems (so you should save and > >> restore the cursor when changing video modes). > > > > Yes, there is but this is not it! Those bits in the equipment flag word > >are for the *INITIAL* video mode. Changing those bits will *not* effect a > >display adapter switch. > > Sorry. Setting the BIOS equipment flag is the correct way to start. THEN > you have to do a video mode switch to an appropriate mode. This is a known > technique that works on a wide variety of machines that I have tried. > [Switch Active Display stuff deleted] Ok, I stand corrected and agree about using Switch Active Display with a Hercules/VGA combination. What you're saying is, start with changing the Equipment word and then to access the Hercules, switch to Video Mode 07. Wouldn't you also have to setup bit 3 at 40:87H and bit 6 at 40:89 (bit 3, 0 = VGA active, 1 = inactive; bit 6, 0 = display switch disabled, 1 = enabled)? Or does the Mode switch take care of this? -- ________________________________________________________________________________ R. Kevin Laux Email: rkl1@hound.att.com AT&T Bell Labs Voice: (908) 949-1160 Holmdel, NJ 07733 Fax: (908) 949-0959