Author Topic: OS/2 4.52 support for MDA monochrome display adapter  (Read 429 times)

Rick C. Hodgin

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OS/2 4.52 support for MDA monochrome display adapter
« on: November 02, 2018, 05:10:13 pm »
Does OS/2 4.52 support both S/VGA and MDA at the same time?  Are there existing drivers for it?
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Bogdan Szmalcownik

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #1 on: November 02, 2018, 09:08:24 pm »
Does OS/2 4.52 support both S/VGA and MDA at the same time?
MDA is only possible for the secondary display.

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Are there existing drivers for it?
Yes.

Rick C. Hodgin

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #2 on: November 03, 2018, 12:39:15 am »
Does OS/2 4.52 support both S/VGA and MDA at the same time?
MDA is only possible for the secondary display.

I think I remember using a monochrome second monitor back in the 90s with Warp 4.

Does it support monochrome graphics and text?
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Bogdan Szmalcownik

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #3 on: November 03, 2018, 01:16:48 pm »
Does it support monochrome graphics and text?
We are speaking about the Monochrome Display Adapter (MDA) which is not capable of doing graphics the APA way.
So the text and effects are the graphics.

You can find more information in the manuals of the debuggers or their additional technical notes. CodeView and Video should work.

Rick C. Hodgin

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #4 on: November 03, 2018, 01:46:59 pm »
Does it support monochrome graphics and text?
We are speaking about the Monochrome Display Adapter (MDA) which is not capable of doing graphics the APA way.

Hercules MDA used two modes:  text, graphics.

These were all in the same 32 KB buffer 0xb0000 - 0xb7fff, which you can see here:  http://www.visual-freepro.org/videos/2014_02_13__exodus_debi_debugger.ogv

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So the text and effects are the graphics.

You can find more information in the manuals of the debuggers or their additional technical notes. CodeView and Video should work.

Mono monitors were great for debugging. They were completely independent of VGA space, including data read/write ports.
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Bogdan Szmalcownik

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #5 on: November 03, 2018, 02:13:16 pm »
Hercules MDA used two modes:  text, graphics.
Unfortunately not true, only the text mode of some Hercules Graphics Cards was compatible to the original Monochrome Display Adapter (MDA). But who's using old 8-bit display adapters in today's systems?

Rick C. Hodgin

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #6 on: November 03, 2018, 02:33:00 pm »
Hercules MDA used two modes:  text, graphics.
Unfortunately not true, only the text mode of some Hercules Graphics Cards was compatible to the original Monochrome Display Adapter (MDA).

I don't understand what you mean.  The graphics mode used 720x348 scan lines, while text mode used 720x350.  I believe the two missing in graphics modes were blanked (just sent as black).

https://en.wikipedia.org/wiki/Hercules_Graphics_Card#Hercules

The Hercules card was essentially an MDA-compatible monochrome card with an added all-points-addressable graphics mode. The card connected to IBM's monochrome 5151 monitor or a third-party monitor compatible with the 5151, and it displayed text and graphics in the same 720×350 pixel resolution format, in the same raster format, and at the same horizontal and vertical scan frequencies as the MDA.

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But who's using old 8-bit display adapters in today's systems?

People interested in doing kernel / driver debugging without otherwise affecting the machine state in any way. :-)
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Olafur Gunnlaugsson

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #7 on: November 05, 2018, 07:54:22 pm »
Does OS/2 4.52 support both S/VGA and MDA at the same time?  Are there existing drivers for it?

Yes it does, you may have to some digging around for the driver, might be on hobbes, text only if I remember it correctly, but i used it for years for text editing as the old MDA screens were much sharper than the SVGA screens of the day.

It has limited use for debugging purposes however since the IBM debugger has already started to communicate via the serial port long before the MDA driver is initialised, so having a small computer such as an old thin client or an embedded industrial platform that you can get off ebay for 5 euros, act as a serial data logger makes much more sense.

Rick C. Hodgin

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #8 on: November 05, 2018, 08:02:09 pm »
[MDA] has limited use for debugging purposes however since the IBM debugger has already started to communicate via the serial port long before the MDA driver is initialised...

My goals are to use a different custom debugger that lets me step through kernel bootup.  It's a debugger kind of like CodeView in disassembly mode.
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Olafur Gunnlaugsson

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #9 on: November 05, 2018, 09:25:45 pm »
[MDA] has limited use for debugging purposes however since the IBM debugger has already started to communicate via the serial port long before the MDA driver is initialised...

My goals are to use a different custom debugger that lets me step through kernel bootup.  It's a debugger kind of like CodeView in disassembly mode.

 ::)

Rick C. Hodgin

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Re: OS/2 4.52 support for MDA monochrome display adapter
« Reply #10 on: November 05, 2018, 09:31:12 pm »
Quote
My goals are to use a different custom debugger that lets me step through kernel bootup.  It's a debugger kind of like CodeView in disassembly mode.

 ::)

 ;)
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