Jo22 wrote:

BitWrangler wrote:

I can't see how you either disabled all RAM above 640k or only installed 640k in the 586 so there was no conflict with existing memory.

That's a good point. All I did was to not enable shadow memory.. The remaining memory was treated as extended memory which begins beyond 1MiB.

Memory between 640k and 1MB is usually not enabled by default, except for ROM shadowing. This is especially true for A000-BFFF which is reserved for video cards.

Since that question came up, just in case this is not common knowledge: A000-AFFF: EGA/VGA graphics modes. B000-B7FF: MDA/Hercules half mode (MDA only has 4kB so in that case only B000-B0FF). B800-BFFF: CGA (graphics and text modes - a true CGA card has 16 kB so actually B800-BBFF), EGA/VGA text modes, second Hercules page in full mode.

BTW, i doubt that a character ROM will make any difference. The character is not accessible by the CPU (not mapped on the ISA bus), it is only used by the video controller.

Perhaps you could try accessing the Hercules memory yourself? (Write, read again and compare.) debug.com should to the trick, but the CLI interface takes a moment to get used to.
I remember I had a memory monitor as a tiny TSR program (typed-in from a computer magazine). For some reason it wasn't compatible with the XT we used (machine hung when TSR got activated), but it worked on lates machines (286+). I can't find a trace on the web, though, and I don't know if I still have it somewhere.

idspispopd wrote:

Perhaps you could try accessing the Hercules memory yourself? (Write, read again and compare.) debug.com should to the trick, b […]
Show full quote

Perhaps you could try accessing the Hercules memory yourself? (Write, read again and compare.) debug.com
should to the trick, but the CLI interface takes a moment to get used to.
I remember I had a memory monitor as a tiny TSR program (typed-in from a computer magazine).
For some reason it wasn't compatible with the XT we used (machine hung when TSR got activated), but it worked on lates machines (286+). I can't find a trace on the web, though, and I don't know if I still have it somewhere.

Thanks for the suggestion! 😀
I'm not vey familiar with debug, though, so I decided to actually use the HGC with an MDA monitor..

I'll do some testing this night and report back soon..

Okay, so let's start! 😄

I've set-up my M35 along with a namless on-board CGA,
Winbond W68855AF Hercules compatible card and a Tandon TC0420.

When I entered MODE MONO, the DOS console switched from CGA card to Hercules
(a frozen image was still shown on CGA):

Afterwards, I ran my copy of Sketch which has built-in Hercules support.
To no surprise, it will mess-up CGA memory space, though.

I guess this is related to the fact that Sketch uses a lot of layers..
The text as seen in the picture is caused by a burn-in damage (not my fault):

Next test, MSD. Microsoft Diagnostics detects the Hercules as a primary video device.

Checkit. When I ran CheckIt! first time, it detected no Hercules card, just an MDA.
It detected 4KiB of RAM.

Luckily, I remembered that in order for using Hercules cards, a TSR, MSHERC, was required..
So I executed it accordingly to the documentation.

When I ran CheckIt! second time, it detected the Hercules card.
It detected 64KiB of RAM.

And gave an error message..

.. which I shortly after found the reason for.

Apparently, MSHERC runs in full-mode by default.
Running it with the more or less undocumented /HALF parameter fixed it for me:

So when I ran CheckIt! a third time, it detected the Hercules card as intended.
It detected 32KiB of RAM.

The memory map looks like this:

Here are two more pictures of the memory map.

First, the memory map as shown in Hercules mode..

..and second, in CGA mode:

Okay, so I also tried umb.sys again.
No luck. 🙁

Edit: I noticed a mistake of mine and fixed it (one "0" too much).
Unfortunately, it had no effect.

Edit: The same issue persists with all three cards I used last time.

Edit: I did a recording of the boot-up sequence and noticed an error message "Command line error !".
Probably caused by UMB.SYS: https://www.youtube.com/watch?v=yNg1paKXAIw
Does anybody know how to exactly use UMB.SYS ? 😕

Things are getting weird.. Seriously. 😒

I gave IBM PC-DOS 6.1 a try, since it was mentioned along with umbherc.sys
at http://www.robvanderwoude.com/dosmem.php .

For some strange reson, the Winbond card was not detected as a Hercules card.
In a second test with MS-DOS 6.2 it was the same case, though, so it likely isn't related to PC-DOS.

Still, PC-DOS 6.1 didn't "fix" anything either when it comes to its own companion driver, umbherc.sys.

The other two cards, Epson Q205A and TD8088A were detected as beeing Hercules compatible, at least.
After waiting for 30 minutes anything to happen, I gave up.

My config.sys looks like this:

DEVICE=UMBHERC.SYS
DOS=UMB

No autoexec.bat.