486 with EGA? (and other EGA related questions)

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486 with EGA? (and other EGA related questions)

Postby MMaximus » 2018-1-30 @ 20:08

Are there any limitations with the type of system that an EGA card can be used with? I have an EGA wonder 800+ that I tried successfully in an XT, a 286-12 and a 386SX-16. I want to assemble an EGA rig and am trying to figure out the best system speed to choose for the games I used to play back in the day on my 8mhz XT (and that I remember being to slow to cope with EGA).

I've just tried the EGA wonder in a PC-Chips m918i motherboard, and it doesn't post. The same mobo posts with an 8-bit VGA card. Is this a BIOS limitation or some sort of incompatibility? In the BIOS settings VGA/EGA is selected for video. The m918i is kind of a late 486 motherboard and it had a Dx4-100 when I got it. I swapped it for the lowest supported CPU, a 486SX-25.

On another note, provided that the motherboard would accept EGA, could EGA bottleneck a system, regardless of how fast the CPU would be? One of the games I've been using to test systems is Activision's 1989 Deathtrack. On VGA, it's too slow in my 10mhz XT. The speed seems adequate on a 286-12 and too fast on the 486SX-25. I wonder if EGA would somehow limit the game speed so that a faster system could be used.

Bonus pics: Some EGA action on my 5153

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Re: 486 with EGA? (and other EGA related questions)

Postby brostenen » 2018-1-30 @ 20:27

I have only used EGA on 286's and 386's. Mostly seen them on 286 system's. As I recall it, people that bought 386's here in Denmark, when they were the new thing. All of them bought their machines with VGA. Schools on the other hand, had 386's with EGA. I guess it was cheaper to go that route. To me EGA is 286 territory, and works wonderfully with that processor.

Nice EGA monitor. Yeah... EGA is a nice thing indeed. And it might be really rare these days, to have a fully working EGA monitor.
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Re: 486 with EGA? (and other EGA related questions)

Postby torindkflt » 2018-1-30 @ 22:32

AFAIK, VGA is backwards-compatible with EGA. All you need to do is find a way to change the mode on the fly, and the VGA card will switch to EGA mode with all the inherent limitations. A basic Tetris clone I got on one of my systems came with a couple utilities to do this, but I imagine it might be possible using the DOS "MODE" command (although I would not know the exact commands to do so off the top of my head).
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Re: 486 with EGA? (and other EGA related questions)

Postby keropi » 2018-1-30 @ 22:54

MMaximus wrote:[...]
I've just tried the EGA wonder in a PC-Chips m918i motherboard, and it doesn't post. The same mobo posts with an 8-bit VGA card. Is this a BIOS limitation or some sort of incompatibility? In the BIOS settings VGA/EGA is selected for video. The m918i is kind of a late 486 motherboard and it had a Dx4-100 when I got it. I swapped it for the lowest supported CPU, a 486SX-25.


What are the odds! Last week I tried the same with an VIA-based 486 motherboard and a 486SX/25. I also found that not all EGA cards work ok:
- the EGAMAX860 will take ~10seconds to begin booting
- a JUKO ega won't boot the system at all

So it appears that 486 is really pushing it when it comes to real EGA cards, it is unfortunate. My vision was to make a slow 486 system with EGA so games won't be slowed down due to cpu/system speed. I haven't tried my EGA WONDER 800+ with the 486 system but reading your experience I am not hoping for much... :dead:

Nice 5153 btw, kudos! :blush:
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Re: 486 with EGA? (and other EGA related questions)

Postby Deksor » 2018-1-30 @ 22:58

Hm I think I could test that as well then. However my "slowest" non OEM 486 is my 5x86 ...


On the other hand apparently even windows 9x can run with EGA so that could be fun to try if that even works on faster machines like pentium or pentium II.
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Re: 486 with EGA? (and other EGA related questions)

Postby Jo22 » 2018-1-30 @ 23:24

torindkflt wrote:AFAIK, VGA is backwards-compatible with EGA. All you need to do is find a way to change the mode on the fly, and the VGA card will switch to EGA mode with all the inherent limitations. A basic Tetris clone I got on one of my systems came with a couple utilities to do this, but I imagine it might be possible using the DOS "MODE" command (although I would not know the exact commands to do so off the top of my head).

Yes, VGA is backwards-compatible to EGA screen modes.
As far as I know, it will use 400 line mode to simulate EGA on VGA monitors.
That is why we see a centered image with a black border surrounding it (640x350 mode displayed as 640x400).
Supporting it natively would be more tricky, since it uses a line frequency of 21,85 kHz (and a different polarity).
What VGA usually does not emulate is the EGA refresh rate (70hz instead of 60Hz) also.
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Re: 486 with EGA? (and other EGA related questions)

Postby Errius » 2018-1-31 @ 08:02

Isn't the 5153 CGA? How are you getting EGA on it?
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Re: 486 with EGA? (and other EGA related questions)

Postby MMaximus » 2018-1-31 @ 16:29

brostenen wrote:...Nice EGA monitor. Yeah... EGA is a nice thing indeed. And it might be really rare these days, to have a fully working EGA monitor.


Errius wrote:Isn't the 5153 CGA? How are you getting EGA on it?


The 5153 is CGA. But like all CGA monitors it can display low-res EGA - 320x200 in 16 colors. I'd love to own a true EGA monitor again, but since most of the games I want to play are in 320x200, I'm quite happy with the 5153. :)

torindkflt wrote:AFAIK, VGA is backwards-compatible with EGA...


Sure, I could stick a VGA card in a 286 and be done with it, and most EGA games would display correctly AFAIK. But I want to play these games like I remember them, 15khz scanlines and all :)

Deksor wrote:Hm I think I could test that as well then. However my "slowest" non OEM 486 is my 5x86 ...


Would be interesting to have some results if you decide on testing on your end, let us know!

keropi wrote:What are the odds! Last week I tried the same with an VIA-based 486 motherboard and a 486SX/25....


Actually I got the idea from you when you suggested me to build an EGA rig with a 386DX40 ;) I have a few 386DX boards but none of them are in working condition. So I figured I would try with this board first. I have another 486DX2/66 that I might try with if I can find the time. The quest continues :cool:
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Re: 486 with EGA? (and other EGA related questions)

Postby Predator99 » 2018-1-31 @ 18:13

Yes, EGA should work in all boards with ISA slots, but I also noticed some incompabilities with card/board combinations

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Re: 486 with EGA? (and other EGA related questions)

Postby keenerb » 2018-1-31 @ 19:12

All of my EGA cards are extremely sensitive to ISA bus speeds, and either have display glitches or fail to work at all when bus speeds get high.
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