Sorry I've not been updating, had a lot going on.

I'm embarrassed to have to ask, but -- does anyone know the proper value for the brightness potentiometer? I've misplaced the original, sadly, and I think it's accidentally gone 🙁

starhawk wrote on 2022-08-16, 14:56:

Sorry I've not been updating, had a lot going on.

I'm embarrassed to have to ask, but -- does anyone know the proper value for the brightness potentiometer? I've misplaced the original, sadly, and I think it's accidentally gone 🙁

Please? I can't use that modeline without a replacement pot, I'm not leaving that input open. It's the same value across all Compaq Portables AFAIK.

The fellow I donated the old parts to, including the missing pot got back to me.

For the record, I was wrong-- for a Compaq Portable II it's a 10k pot, for the Portable IIIs (and, presumably, the Portable 386, which uses a lot of the same chassis and internal parts, but a VERY different motherboard) is 40k. Good luck with that one, I suppose...

Well, at least 10k pots are easy to find, even if that particular shaft design almost certainly is not...

Got the brightness pot sorted, and guess what?

Did a preemptive multimeter check between power and ground, just to be on the safe side... I swear it was fine before I pulled it, cakewalk, right?

NOPE. 34 ohms between power and ground 🙁 this miiight be a while, folks.

Afaik, there also was Super EGA (SEGA)..

Never heard of that! Do tell...?

starhawk wrote on 2022-08-29, 20:29:

Never heard of that! Do tell...?

@Jo22 -- still intrigued. Plz inform.

starhawk wrote on 2022-08-29, 03:58:

Got the brightness pot sorted, and guess what?

Did a preemptive multimeter check between power and ground, just to be on the safe side... I swear it was fine before I pulled it, cakewalk, right?

NOPE. 34 ohms between power and ground 🙁 this miiight be a while, folks.

Fault traced to a weakly-shorted TDA1170N 🙁 short appears between Pin1 and heatsink (0v GND) flanges... replacement chip will be here Tuesday, at considerable expense -- but I have a deadline, so... 😒

I just found this interesting video on the topic.
https://www.youtube.com/watch?v=bU2im8XXNr8

Interesting. Didn't have much tech info, but... interesting.

TDA1170N repair appears successful; operational testing will commence after lunch.

The Schneider Tower AT is said to support 800x600. It came with a multisync monitor, and had a GEMINI VC-001 EGA chipset with 256kByte graphics RAM.
AFAIR I once tried in in Win 3.1 (must be 20 years ago), and it was flickering like hell.
I also remember Ironman Super Offroad offering a 64 colours mode on EGA, which only worked with multisync monitors (regardless of Extended EGA or not).

starhawk wrote on 2022-09-13, 16:48:

Interesting. Didn't have much tech info, but... interesting.

TDA1170N repair appears successful; operational testing will commence after lunch.

Broke instantly 🙁

citronalco wrote on 2022-09-13, 23:28:

The Schneider Tower AT is said to support 800x600. It came with a multisync monitor, and had a GEMINI VC-001 EGA chipset with 256kByte graphics RAM.
AFAIR I once tried in in Win 3.1 (must be 20 years ago), and it was flickering like hell.
I also remember Ironman Super Offroad offering a 64 colours mode on EGA, which only worked with multisync monitors (regardless of Extended EGA or not).

I did some testing on that machine yesterday. The Gemini VC-001 EGA Hires works with my MCE adapter on my Nec 71VM.

What does work, what does not work:
- All textmodes seem to work, even the wiered resolutions
- Lowres EGA and EGA Hires works just great (320x200 and 640x350)
- Extended EGA does work in Sketch 3.0 and Windows 2.x (640x480 + 800x600)

What does not work:
- There is no image viewer in Dos that can display extended EGA modes like 640x480 and 800x600. It should work, but the monitor is switched of "no signal"
- Because win2x cuts the palette there are no real 16colors available, so Paintbrush 1x does not show the full 16color images for EGA
- if the Bios is set to "multiscan+EGA-Hires" the 40colum modes do not work on Nec 71vm, if the Bios is set to "multiscan70hz+EGA-Hires" the 40colum modes do work on Nec71vm.
- The driver disk seems to offer more windows-drivers, they are dated to 1988+1987, so perhaps not Win3 drivers. I tested them, Windows 3.0 does not work with them. Win1x does not offer a display-driver-installation" out of the box. (see content eg3000.zip). Next I will try the other drivers.

Doc

yesterday I found an old cracktro that offers EGA scene effects in high quality. It's the cracktro to M1-tank platoon.
The Logo-effect on the bottom looks like the effect that is used to generate the famous "water ripples" that
looked like pixelshader on the CGA demo AREA5150. By the way the best gfx-effect I have ever seen on a XT.

dr.zeissler wrote on 2025-01-20, 09:04:

- The driver disk seems to offer more windows-drivers, they are dated to 1988+1987, so perhaps not Win3 drivers. I tested them, Windows 3.0 does not work with them. Win1x does not offer a display-driver-installation" out of the box. (see content eg3000.zip). Next I will try the other drivers.

Hi, sorry for intrusion.. I just want to say that Windows 2.03 drivers sometimes work in Windows 3 Real-Mode (but not WIN386 aka Windows/386 drivers).
And since this PC is an AT, it might be necessary to run WIN /R to force Windows 3 into Real-Mode.
The Windows 2 drivers never worked in Standard-Mode to me, at least.

Thx, Jo22 I'll test that.

it works, but it is a bit strange...

1. Win2x/286 does work in extended EGA up to 800x600. But the full 16colors seem to be not supported, or occupied by windows itself.
2. Win2x/286 can only make use of 64KB extenden memory if the himem.sys is loaded an dos does not use it via "dos=high" which gives even less free dos-memory.
3. Win30 can make use of the full 2MB Ram when using EGA standard-drivers 640x350
4. Win30 can make use of extended EGA modes 640x480/800x600 only in real-mode so the free RAM is pretty low.

in german we would call that "weder Fisch noch Fleisch".

Hi, I see, makes sense.

Windows 2 uses 8 colours for the GUI, but 256c colour drivers do principally work.
It's just the palette system that's odd.

Probably because of the virtual thru-color system (always uses dithering for that).
The Tandy 2000, which Windows was made on had 640x400 8c.
Early NEC PC-9801 machines had an 8 colour limit, too.

Easel picture viewer can view some GIF87a pictures with 236c nicely, while others do have weird colour banding effects (I use xnView for Win32s to write GIF87a files).

Windows in Real-Mode (any version) causes me memory headaches, too.
I consider buying an modern EMS card for my Commodore PC10.
There are 2 and 4 MB models, I think..

Anyway, I think it would be useful for GeoWorks Ensemble, too.

Maybe 4 MB, to have similar amount of RAM like an 286 running Windows 3.1 or OS/2 ?

On other hand, I remember the limit for a single EMS board being 2 MB because of the EMS addressing scheme.

So the 4 MB models sold do sort of create a virtual EMS board by using 2 cards with 2 MB each ?
If so, I wonder if this causes any compatibility issues.

LoTech Board 2MB does not work. No support on chipset.

Oh. Then the only idea that comes to mind is to write a VBE TSR for 800x600 16c (mode 6Ah or 102h) and then use the Super VGA driver supplied with Windows 3.1 (800x600 16c) or 3.1 Beta.

This may work, since both EGA/VGA are near identical in terms of 16 colour default palette (640x350 16c and 640x480 16c start with 16c EGA palette).

That's also why some late EGA cards like ATI EGA Wonder 800 (+) could display VGA mode 12h (640x480c 16c).

Provided, that the palette hadn't been reprogrammed by the application.
Some VGA applications do that, they don't consider that an EGA card without a RAMDAC is in the system.

But to my understanding, Windows 3 standard VGA driver doesn't use a custom palette (if it's custom, then close to EGA).
Theres a separate, palettized VGA driver in Windows 3.0 MME for that.

Edit: Or other way round, we must patch supervga.drv to use 800x600 16c video mode of the GEMINI VC-001.
At the simplest, change 6Ah mode number for the GEMINI VC-001 mode number by using a hex editor.

Edit:

LoTech Board 2MB does not work. No support on chipset.

Btw, do you know if there's any chance that the LoTech card works in Windows 2.x ?
Because full-fledged applications like Word for Windows seem to consume about a massive 1,5 MB of RAM..

Edit: I'm a bit confused by this one:

Software Support […]
Show full quote

Software Support

The 1MB-RAM-Board doesn't need any device drivers, since the system BIOS will automatically detect the RAM (up to 640KB)
The 2MB-EMS-Board requires:
A LIM EMS Device Driver (the device driver for the 2MB EMS board is LTEMM.EXE)
Software supporting the LIM EMS standard, such as Lotus-123, Microsoft Windows 2 and 3.0, and some games.
The Lo-tech EMS Board Test Utility can assist with hardware testing after build.

Source: https://www.lo-tech.co.uk/wiki/Lo-tech_Memory_Board_FAQ

So is the Lo-Tech driver conpatible with Windows 2.03 or not? 😟