With a little help from my friends.

[Enrique]

As was looking for a forum in the internet dealing with MS-DOS, and wasn't very successful. Does somebody know a quality DOS forum (it could alsa be a mailing list)?

[Chris]

I don't know of anything like that, but I worked a lot with DOS, and if you just have a question, I might be able to answer it.

[Enrique]

This is a PC with PCI expansion bus. It happens it has an ISA slot for backwards compatibility. In this, I can and I did plug in an Hercules graphics adapter as a secondary display adapter.

OK, this is the problem: No operating system system I've run on the machine is able to use the secondaty adapter. I see no output on the secondary monitor. And MS-DOS 5.00, which is one O.S. I'm running on the PC is no exception, it presents a blank screen (the cursor can be seen, though).

[Sorrano]

Not sure if this is helpful:

http://support.microsoft.com/kb/44236

How much memory does the PC have? That might limit the ability to run multiple screens.

[Enrique]

There are 256MB of RAM in this machine. In the article they speak about the second mode an Hercules can be operated on: graphics mode. The first mode is text mode. So, the article is of no help to me, as the Hercules should operate in text mode upon leaving machine boot. But thanks anyway for your post Sorrano.

[Sorrano]

You may need more memory, Enrique. One of the issues I saw is not enough RAM. Also, make sure there are no conflicts with the interrupt settings on the adapter. It's been a long time since I dealt with MS-DOS, but those interrupt settings are rather important. Seems like the sound card was usually set on 5 and the printer on 7. There may be jumpers on the adapter, too, that will toggle the ability to use 2 screens. Have you looked at the BIOS settings of the computer, as well?

[Enrique]

I see I did not make myself clear. The monochrome adapter is the secondary display and is in an ISA slot. The color monitor I connect it to the motherboard onboard connector, which I call primary display, Sorrano. So the mono adapter (Hercules card) has no need for two screens. Hummm... I see. You mean the Hercules jumpers (and it has only two of them, JP1 and JP2) must be properly set for computer to use two monitors? Because I played a bit with the four possible combinations (open, close).

The fact is that, in the BIOS setup menu, the RAM begining at B0000 is not available. Only C0000 is. But mono displays use B0000 (and B8000). So I think this is a definitive NO for me.

[Chris]

OK, this is the problem: No operating system system I've run on the machine is able to use the secondaty adapter. I see no output on the secondary monitor. And MS-DOS 5.00, which is one O.S. I'm running on the PC is no exception, it presents a blank screen (the cursor can be seen, though).

What are you trying to show on the second monitor? DOS did not natively support multiple monitors, so the only way you are going to get something to show up there is if you are running a program that knows the memory address the Hercules card uses and directs output there.

[Enrique]

Alright, that's news for me, and I think it's a good bit of information. I want to use linux on that machine. As I have problems setting up linux to manage the Hercules, I decided to investigate the thing under DOS. Here's what I'm presently about to do. I have an assember source which, not making use of the BIOS nor DOS ints, tries to identify both primary and secondary video systems. Running that will be a starting point.