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phreakindee
September 5th, 2010, 02:20 PM
I was talking to this guy online and he was saying he uses a 5153 CGA monitor hooked up to an EGA card on his IBM 5150. Apparently this was because he couldn't find an EGA monitor, like the 5154, and instead just uses EGA on the 5153. I thought maybe he meant he uses CGA mode on an EGA card and it works, but he's claiming EGA graphics are working on the 5153.

This sounds weird to me. It was my understanding this shouldn't work. Am I wrong?

per
September 5th, 2010, 02:23 PM
It works, but you only get the 16-colour modes.

modem7
September 6th, 2010, 03:04 AM
The IBM EGA card has switches, which are set according to which monitor type is attached. That information and the video modes supported for a particular monitor type are in the 'IBM Enhanced Graphics Adapter' document at http://members.dodo.com.au/~slappanel555/oa/oa.htm (note: slow web site).

Maverick1978
September 6th, 2010, 07:58 PM
I recently picked up a Paradize EGA card, but have yet to try it out with my 5153 - am somewhat worried that I'll have the wrong dip switch set, or enable the wrong mode and fry my monitor. Gotta get past that - one of these weeks when I get some time.

james1095
September 8th, 2010, 03:47 PM
I've had the exact same setup for years, it works fine. What doesn't work is anything that uses the higher resolution EGA mode, but even with the 5153, it's a big improvement over CGA.

james1095
September 8th, 2010, 03:49 PM
Oh and YMMV of course, but the 5153 is a pretty robust monitor, and I have never managed to fry one. I would not advise leaving it running long if the picture is scrambled due to feeding it an unsupported mode, but you will be fine to test.

EddieDX4
September 11th, 2010, 09:41 AM
I was talking to this guy online and he was saying he uses a 5153 CGA monitor hooked up to an EGA card on his IBM 5150. Apparently this was because he couldn't find an EGA monitor, like the 5154, and instead just uses EGA on the 5153. I thought maybe he meant he uses CGA mode on an EGA card and it works, but he's claiming EGA graphics are working on the 5153.

This sounds weird to me. It was my understanding this shouldn't work. Am I wrong?

Most non-IBM EGA cards had switches to allow them to "skip" the high-res EGA frequency scan modes when a text mode is invoked (e.g. during initial boot by the BIOS), so that it can be used with a CGA monitor. In some cards, this would be listed as a "80x25 CGA" mode, if there's any DIP switch reference included.

You still get 320x200x16, 640x200x16, and all 80x25 text modes (color/b&w). One thing you may notice, however, is that some colors (brown, for instance) will not look as natural on a CGA monitor as they do on a real EGA.

At one point, I had a Tandy CM-11 driven by an EGA card for many years. In reality, most DOS EGA games used 320x200x16 color mode, so this setup will work with most. Games that use 640x200 "mid-res" EGA modes should work as well. Obviously, anything that expects high resolution will not work at all, although the game/app will not freeze up or show a blinking cursor, as it would when you attempt to run an EGA game using a CGA display adapter, but rather it will simply cause the CGA monitor to go out of its frequency range (a high pitch hissing will usually accompany the fast flickering/spinning screen). A good example of this is SimCity, if you do not start it with the /de command (the EGA auto detect assumes it can also do high res, so it defaults to the equivalent of /dE...the lower case 'e' forces 320x200x16 instead of 640x350).

tezza
September 11th, 2010, 11:38 AM
I was talking to this guy online and he was saying he uses a 5153 CGA monitor hooked up to an EGA card on his IBM 5150. Apparently this was because he couldn't find an EGA monitor, like the 5154, and instead just uses EGA on the 5153. I thought maybe he meant he uses CGA mode on an EGA card and it works, but he's claiming EGA graphics are working on the 5153.

This sounds weird to me. It was my understanding this shouldn't work. Am I wrong?

My IBM AT has this kind of set up. EGA card but CGA monitor. Seems to work ok for 16 colours and certainly the text is much clearer than using a CGA card.

Tez

Raven
September 12th, 2010, 09:01 AM
I never thought along this avenue before.. is there a way to do CGA on a MONO monitor, and just deal with the lack of color? I know there are monochromatic CGA screens, but I mean an ordinary monochrome monitor..?

EddieDX4
September 12th, 2010, 11:09 AM
I never thought along this avenue before.. is there a way to do CGA on a MONO monitor, and just deal with the lack of color? I know there are monochromatic CGA screens, but I mean an ordinary monochrome monitor..?

Depends on the monitor. If it can do both high and low frequency scan modes, you should be able to use it for CGA (200 lines) or text-only at the equivalent of 348 lines. I think this was what Hercules initially took advantage of to display high-res graphics on existing mono displays.

Some might only support one or the other.

JohnElliott
September 12th, 2010, 11:11 AM
Not with an IBM CGA card, but this can be done with the ATI Graphics Solution.

per
September 12th, 2010, 11:20 AM
I never thought along this avenue before.. is there a way to do CGA on a MONO monitor, and just deal with the lack of color? I know there are monochromatic CGA screens, but I mean an ordinary monochrome monitor..?

If you got any kind of ATI graphics card from the 80's, you can do that.

In fact, the very first graphics card ATI made (the ATI Color Emulation Card) was designed to do exactly (and only) that. They soon upgraded it to the "Graphics solution plus", which were again expanded and made into the high-end "EGA Wonder" and mid-end "graphics solution - SingleChip" (or better known as "Small wonder Graphics Solution"). From there, the EGA wonder was upgraded to the original VGA Wonder, which still maintained cirquits (allthough sligthly different compared to previous products) for greenscale graphics on a mono monitor.

The TTL-level Digital-out port was scrapped durning the production span of the ATI VGA Wonder 1024, and has never appeard again on any ATI card after that.

hargle
September 12th, 2010, 12:38 PM
this is really interesting to me too.
i might have a couple EGA cards lying around that i've never used because i didn't think i could use one without a monitor.
What I'm really curious about though, is that we had this discussion on CGA modes on VGA cards, and that lots of VGA cards can't properly do the CGA modes for whatever reasons. So I've kept a true CGA card in my machine just in case I wanted to do some gaming that only works on specific CGA devices. Now I'm thinking that perhaps an EGA card might be more backwards compatible friendly for doing some of the weird CGA modes that some games utilize... This could perhaps be the best of both worlds.

What I *really* want to do is instead of using a 5153 monitor, use my PCjr monitor instead, but have it KVMed between my 3 CGA machines. I really need to explore this! thanks for starting this thread.

per
September 12th, 2010, 01:17 PM
What I'm really curious about though, is that we had this discussion on CGA modes on VGA cards, and that lots of VGA cards can't properly do the CGA modes for whatever reasons.
Well, I thought the BIOS modesworked all rigth, but that many VGA cards can't do some special CGA tricks (in VGA-Configuration at least) because of I/O register differences.


Now I'm thinking that perhaps an EGA card might be more backwards compatible friendly for doing some of the weird CGA modes that some games utilize... This could perhaps be the best of both worlds.
I'm sorry to say I doubt it. As I stated above, the I/O registers in the VGA works sligthly different than the corresponding I/O registers in the CGA. The EGA registers works in much the same way as the VGA registers, and that's the reason for my doubt.

However, as I stated in my post above, the early ATI VGA wonder cards can be configured to almost perfectly emulate MDA/CGA/Hercules/etc. on almost any monitor. Mikey99 once scanned the box showing the table of supported configurations/monitors, but those scans has been taken down from the internett a long time ago.

mikey99
September 12th, 2010, 06:16 PM
.....Mikey99 once scanned the box showing the table of supported configurations/monitors, but those scans has been taken down from the internett a long time ago.

Hi per , I'm honored that you remember those scans :-) ...... So I dug up my old post and put the url's here ....

Here's the ATI VGA Wonder box scans:

http://www.vintage-computer.com/vcforum/attachment.php?attachmentid=1411&d=1235105179

http://www.vintage-computer.com/vcforum/attachment.php?attachmentid=1412&d=1235105588

http://www.vintage-computer.com/vcforum/attachment.php?attachmentid=1413&d=1235106272

Here's the original thread for the discussions :
http://www.vintage-computer.com/vcforum/showthread.php?14364-IBM-Portable-PC-5155

JohnElliott
September 13th, 2010, 01:17 PM
this is really interesting to me too.
i might have a couple EGA cards lying around that i've never used because i didn't think i could use one without a monitor.
What I'm really curious about though, is that we had this discussion on CGA modes on VGA cards, and that lots of VGA cards can't properly do the CGA modes for whatever reasons. So I've kept a true CGA card in my machine just in case I wanted to do some gaming that only works on specific CGA devices. Now I'm thinking that perhaps an EGA card might be more backwards compatible friendly for doing some of the weird CGA modes that some games utilize...

A true-blue IBM VGA or EGA card is just as incompatible with the CGA as any later card. What some manufacturers did (notably Paradise Systems) was include a mode on their cards that was compatible with CGA at the register level -- usually selected with a utility, though some cards could also do it by dipswitch.

This can make things complicated. For example, the Amstrad PC1640 has a Paradise chipset, and could be supplied with three different monitors (mono, CGA and EGA). You could then set the dipswitches for at least five possiblities:
* Mono monitor, MDA/Hercules graphics
* Mono monitor, EGA graphics (only supports 640x350 mono graphics)
* CGA monitor, CGA/Plantronics graphics
* CGA monitor, EGA graphics (supports up to 640x200x16)
* EGA monitor, EGA graphics (supports up to 640x350x16)

EddieDX4
September 19th, 2010, 10:42 PM
I just wanted to add to this thread by saying that EGA games at 320x200x16 on a true EGA monitor (in my case, I'm testing this with an IBM 7534, industrial version of the 5154) look substancially better than on a CGA/RGB monitor hooked to an EGA card. The "Specifications" section of the EGA Wikipedia article explains why, but all technical mumbo jumbo aside, it truly is noticible. Scenes in games have more "natural" looking browns, and sometimes some of these shades are lost in CGA. Some games that I thought had horrible 16 color graphics came to life on a true EGA monitor. These tests were made using the monitor mentioned above, and a Tandy CM-11, on a Tandy 1000 TL/2 computer.

Here's the excerpt from Wikipedia:

"The EGA uses a female 9-pin D-subminiature (DE-9) connector which looks identical to the CGA connector. The hardware signal interface, including the pin configuration, is largely compatible with CGA. The differences are in the repurposing of three pins for the EGA's secondary RGB signals: the CGA Intensity pin (pin 6) has been changed to Secondary Green (Intensity); the second ground of CGA (pin 2) has been changed to Secondary Red (Intensity), and pin 7 (Reserved on the CGA) is used for Secondary Blue (Intensity). If the EGA is operated in the modes having the same scan rates as CGA, a connected CGA monitor should operate correctly, though if the monitor connects pin 2 to ground, the shorting of the EGA's Secondary Red (Intensity) output to ground could conceivably damage the EGA adapter. Similarly, if the CGA monitor is wired with pin 2 as its sole ground (which is poor design), it will not work with the EGA, though it will work with a CGA. Finally, because of the use of the CGA's Intensity pin as Secondary Green, on a CGA monitor connected to an EGA, all CGA colors will display correctly, but all other EGA colors will incorrectly display as the standard CGA color which has the same values for the g, R, G, and B bits (ignoring the r and b bits.) Conversely, an EGA monitor should work with a CGA adapter, but the Secondary Red signal will be grounded (always 0) and the Secondary Blue will be floating (unconnected), causing all high-intensity CGA colors except brown to display incorrectly and all colors to perhaps (but probably not) have a blue tint due to the indeterminate state of the unconnected Secondary Blue."

http://en.wikipedia.org/wiki/Enhanced_Graphics_Adapter

Maverick1978
September 20th, 2010, 12:33 PM
Thanks, Eddie... here I was hoping to not have to track down an EGA, but noooooo... you've gone and blown that out of the water! ;)

Actually, I'm still looking forward to trying out my Paradise card with my 5153 - just to see. I didn't know it was possible until this thread!

EddieDX4
September 20th, 2010, 01:39 PM
Thanks, Eddie... here I was hoping to not have to track down an EGA, but noooooo... you've gone and blown that out of the water! ;)

Actually, I'm still looking forward to trying out my Paradise card with my 5153 - just to see. I didn't know it was possible until this thread!

The EGA+5153 works great, but you're limited to the 16 "CGA" colors. I knew EGA could display 64 colors, with the adapter limited to 16 at a time, but I never knew what a big difference it makes on a properly programmed EGA game. One great example is SimFarm. During the intro, where it shows a cow rendered in 640x350, I swear it looks like it is using a VGA palette. Also, the party character avatars in Eye of the Beholder look beautiful on an EGA monitor vs on the CM-11 (the latter looks more "vibrant", but on EGA you can see multiple shades of the same color used, at times up to 3...you lose that detail on a CGA monitor).