kebsch@peun33.sni.de (Kebsch) (01/02/91)
Hi, I am running a Paradise Autoswitch EGA 480 Card with Windows-3.0 in my AT-386. Currently I have configurated the Standard EGA Mode (Mode 10h, 640 rows and 350 lines, 16 colors, video page at A0000). Now my question. What should I do, if I want to run the enhanced EGA Mode (Mode 50h, 640 rows and 480 lines, 16 colors, video page at A0000)? The difference between both Modes are the "Mode Code" (10h <-> 50h) and the numbers of available lines (350 <-> 480). Is it possible to take a copy of the standard EGA driver and patch it? Is it a silly idea? :-) Waldemar -- Waldemar Kebsch, c/o SIEMENS NIXDORF Informationssysteme AG, STO SI 355, 4790 Paderborn, Federal Republik of Germany Email (USA): kebsch.pad@nixdorf.com | Phone: (+49) 5251 146151 Email (Eunet): kebsch.pad@sni.de | Fax : (+49) 5251 146108
hst@mh_co2.mh.nl (Klaas Hemstra) (01/04/91)
From article <kebsch.662804520@peun33>, by kebsch@peun33.sni.de (Kebsch): > > Hi, > > I am running a Paradise Autoswitch EGA 480 Card with Windows-3.0 in > my AT-386. Currently I have configurated the Standard EGA Mode > (Mode 10h, 640 rows and 350 lines, 16 colors, video page at A0000). > >.... > Is it possible to take a copy of the standard EGA driver and patch it? > Is it a silly idea? :-) > > Waldemar Yes of course it is possible to patch a driver. In your case you should take the VGA driver (install as VGA ??), and patch that driver. I tried patching drivers with other software (Framework, Paintbrush) recently and it works fine (in my case to change VGA to SVGA 800x600). In you case it is simply changing a video mode number from VGA 640x480x16 colours (13H i beleive) to another (50H in your case wasn't it ?) Wel first look at the driver with PCTOOLS or something, and search for a machine code that can be recognized. In most cases a search for "CD 21" will do the trick. Check if the expected mode number is located just before the found "CD 21". Mostly it's only a few bytes away. Mark the positions you found. Then go into the standard dos "debug" with the driver as file. In case of Windows you can do it with "debug vga.drv". Then Unassemble the code at the position(s) you found. (Please note that the actual code is located 100H bytes higher because debug treats the file as a binary (e.g. COM) program.) This way you can sort of "read" the driver code. Mostly only a few positions need to be checked and you can determine the right one easily. Change the mode number and try it. If it does not work then it's only an evening of work. In some other cases you have to change some parameters like 80H (width of the screen in bytes) or 01 E0 (= 480 = lines on the screen) to other values. This is a little more difficult but with a bit of trying it can be done ! If you came this far reading this very technical explanation i wish you gould luck if you want to try it. Of course you should make copies of the files (drivers) that you change. Hope anyone is interested, Klaas Klaas Hemstra (hst@mh.nl) | / / ,~~~ ~~/~~ uucp: ..{uunet!}hp4nl!mh.nl!hst | /--/ `-, / ___ |_/ |__| Multihouse N.V., Gouda, the Netherlands | / / ___/ / --- | \ | | "Most of us mindreaders are atheist, you know" A song for Lya: George Martin