mrwittma@phoenix.Princeton.EDU (Martin R. Wittmann) (11/27/89)
I'm looking for a CGA emulator for an EGA card/display on behalf of a friend, so his 4 year old daughter can play some games he has on his PC. A quick perusal of a recent index file from Simtel20 didn't turn up anything. Any leads to such a program in public domain or shareware would be greatly appreciated. Please email! Thanks a lot, Martin Wittmann mrwittma@phoenix.princeton.edu
rh1m+@andrew.cmu.edu (Rudi Jay Halbright) (11/28/89)
CGA software should run w/o modification on an EGA. Ask your friend to try it. -Rudi Halbright rh1m@andrew.cmu
bcw@rti.UUCP (Bruce Wright) (11/28/89)
In article <QZQP8Qe00WB6AlN2I6@andrew.cmu.edu>, rh1m+@andrew.cmu.edu (Rudi Jay Halbright) writes: > CGA software should run w/o modification on an EGA. Ask your friend to > try it. This is not quite true. Most (90+%) CGA software will run properly on an EGA without modification, but the EGA does not provide 100% emulation of a CGA. For example, there are several registers in the controller which either mean different things or which are simply ignored on the EGA. The most common problem is that the colors come out wrong (but still readable) on the EGA, which is unfortunate but not a disaster. There are other possible incompatibilities which can cause things to fail to work at all, but very little software ever used them. There are some programs floating around which attempt to set up the EGA to reduce the probability of problems. I don't have any experience with them (I haven't encountered anything that I couldn't persuade to run after a reasonable fashion), so I can't make any comments on which ones work best or how often they fix the problems, but I know they exist. Your friend should still try running the CGA software on the EGA if it hasn't already been tried - the probability is overwhelming that it will work acceptably on the EGA. Bruce C. Wright
akcs.graf_e@tronsbox.UUCP (Graf Eberstein) (12/02/89)
>Item: 26 by *Masked* at phoenix.Princeton.EDU >Author: [Martin R. Wittmann] > Subj: CGA emulation on EGA??? > Keyw: CGA emulation, EGA Technically, your EGA card should be able to switch into lower resolution modes on its own. If not, check the manual for forcing CGA with a DIP switch or jumper (obvious disadvantage). Finally, the EGA card should have come with driver software. Check that software for a switching program. Finally, what card is it we're talking about?
horvath@granite.cr.bull.com (John Horvath) (12/12/89)
> I'm looking for a CGA emulator for an EGA card/display on behalf of a > friend, so his 4 year old daughter can play some games he has on his PC. If you have EGA and BIOS, then you already have a CGA emulator in the BIOS. Which works fine UNLESS the CGA program tries to set the graphic mode by attempting to directly set the CGA's CRTC registers. Its OK on CGA displays but when the program is run with EGA, the CRTC registers aren't equivalent and get set to irrelevant values that screw up the EGA display mode. Fortunately, most CGA programs set the graphics mode using BIOS and are compatible with EGA and VGA. You probably wouldn't have asked about this unless you tried running the program and it bombed out. By chance is the CGA program your friend is trying to run, one of the Sesame Street games published by Hi Tech Expressions? I got one of these for my daughter and was unable to run it on a VGA display. It would start up and then go into blizzard mode. Using the Turbo debugger I found it was setting the CRTC registers directly instead of using BIOS. So I wrote a patch for it to use BIOS instead. (while I was in there I also patched out that stupid song. No one should be forced to listen to the theme to sesame street more than once a day. :{} ) I wrote twice to the distributer without any response, so I guess they don't support this anymore. I can email the patches for the "big bird's special delivery" game or specifics about how to find this code in other programs. John Horvath Internet: horvath@granite.cr.bull.com mail: Bull HN Information Systems Inc MA30-824A 300 Concord Road Billerica, MA 01821 USA