Usually you get such image when the convergence magnets on the CRT tubes are moved, maybe monitor experienced some shocks during transportation, or someone was inside already.
I tuned the stuff on old TVs, but this is dangerous, as there are high voltages around the controls.

http://www.arcaderepairtips.com/2014/02/28/mo … nvergence-tips/
https://www.youtube.com/watch?v=LvJC6f2dhww

Yeah, the yoke or the convergence magnets have shifted. With luck you can see the original positioning and can restore things. Chances are some plastic tab has broken from having gone brittle from the heat they're in and that has allowed things to move to where they're not supposeud to be. In any case, going inside is unavoidable.

vstrakh wrote on 2023-03-20, 11:45:

Usually you get such image when the convergence magnets on the CRT tubes are moved, maybe monitor experienced some shocks during […]
Show full quote

Usually you get such image when the convergence magnets on the CRT tubes are moved, maybe monitor experienced some shocks during transportation, or someone was inside already.
I tuned the stuff on old TVs, but this is dangerous, as there are high voltages around the controls.

http://www.arcaderepairtips.com/2014/02/28/mo … nvergence-tips/
https://www.youtube.com/watch?v=LvJC6f2dhww

Tiido wrote on 2023-03-20, 12:51:

Yeah, the yoke or the convergence magnets have shifted. With luck you can see the original positioning and can restore things. Chances are some plastic tab has broken from having gone brittle from the heat they're in and that has allowed things to move to where they're not supposeud to be. In any case, going inside is unavoidable.

Thank you both for your answers/directions!
I looked at the yoke, but looking the paint markings it doesn't seem to have shifted. Will look further into the convergence magnets. Hopefully something to do there.
I do see signs of a drop though... so not happy about that. Will report any progress here.
Thanks again.

That wasn't so difficult!
After reading the article in the provided link and watching the video thoroughly I looked at the yoke again. I noticed that the last ring might have shifted, when following the paint markers again.
I put it in the position that looked most fitting, and what do you know. It made quite the difference!
Thank you all for the advice and directions.

Focus is bit off. Try to adjust "F" or focus knob on the flyback transformer.

Cheers,

Yeah, that is definitely a lot better, and focus should get adjusted too ~

It actually only looks blurry when I take a picture with my phone, couldn't get the camera focus right.

I had to have to adjust the focus though because it was way off. I also notice that the image turns brighter when the monitor warms up.
For now the monitor produces a nice enough image to be accompanied by my 5170 😀

Thanks a lot for help!

Nice - never really heard about that 'Taxan Gold' card, although given the chipset I suppose we can make an educated guess at its capabilities.
There's one ad where its 640x400 mode is named "TGA"... "T" for Taxan? 😀

Any chance you'd be willing to provide a dump of its video BIOS? (can be done in software, e.g. NSSI or similar.)

VileR wrote on 2023-03-23, 11:35:

Nice - never really heard about that 'Taxan Gold' card, although given the chipset I suppose we can make an educated guess at its capabilities.
There's one ad where its 640x400 mode is named "TGA"... "T" for Taxan? 😀

Any chance you'd be willing to provide a dump of its video BIOS? (can be done in software, e.g. NSSI or similar.)

That is a nice find of the ad!
There is very little to find about this "Gold Card" unfortunately. Would be nice to find some information about the switch settings, though there is some printing on the pcb.

I have attached some pictures of the card.
After the weekend I might have time to make a dump of the BIOS. I have a programmer so that shouldn't be an issue.

jg77 wrote on 2023-03-23, 14:59:

That is a nice find of the ad!
There is very little to find about this "Gold Card" unfortunately. Would be nice to find some information about the switch settings, though there is some printing on the pcb.

I have attached some pictures of the card.

Hm, you may have seen this on archive.org - Taxan Gold Card DOS drivers. In addition to the files mentioned in the notes, it also includes an "EGA.EXE", which seems to be a general configuration utility for the card.
From looking at the .EXE, I can tell a couple of things:

- It also has a Plantronics ColorPlus compatibility mode (not all that useful in an EGA card, but interesting)
- It's closely related (or may even be the same) as one of the Paradise AutoSwitch EGA models. Which makes sense, given the chipset, and the "AUTO SW-OFF" printing next to the the first switch in your photo.

So if some info exists on a 400-line-capable Autoswitch EGA, it may also be applicable to the Taxan.

After the weekend I might have time to make a dump of the BIOS. I have a programmer so that shouldn't be an issue.

Nice, appreciated!

VileR wrote on 2023-03-23, 19:43:

Hm, you may have seen this on archive.org - Taxan Gold Card DOS drivers. In addition to the files mentioned in the notes, it a […]
Show full quote

jg77 wrote on 2023-03-23, 14:59:

That is a nice find of the ad!
There is very little to find about this "Gold Card" unfortunately. Would be nice to find some information about the switch settings, though there is some printing on the pcb.

I have attached some pictures of the card.

Hm, you may have seen this on archive.org - Taxan Gold Card DOS drivers. In addition to the files mentioned in the notes, it also includes an "EGA.EXE", which seems to be a general configuration utility for the card.
From looking at the .EXE, I can tell a couple of things:

- It also has a Plantronics ColorPlus compatibility mode (not all that useful in an EGA card, but interesting)
- It's closely related (or may even be the same) as one of the Paradise AutoSwitch EGA models. Which makes sense, given the chipset, and the "AUTO SW-OFF" printing next to the the first switch in your photo.

So if some info exists on a 400-line-capable Autoswitch EGA, it may also be applicable to the Taxan.

After the weekend I might have time to make a dump of the BIOS. I have a programmer so that shouldn't be an issue.

Nice, appreciated!

Hi,

I tried to dump the rom using my TL866II-Plus programmer. I had to disable Check ID to get a reading, although I had set Xgpro to the NMC27C256Q IC.
Running latest version of the program and flashed the programmer to the latest firmware.

Please find attached the binary file, but you might want to check if it looks alright.

I will have a look at the files on Archive.org! Thank you for finding those.
I did find the manual for the Paradise AutoSwitch EGA Card, which also has a 6 lever dip switch. Though that's as far as the similarities go. The chip on the Paradise is the PEGA1 and the crystal oscillators are a different MHz. Will keep looking!

jg77 wrote on 2023-03-29, 18:42:

Please find attached the binary file, but you might want to check if it looks alright.

The dump is alright. The BIOS seems to be split into two banks of 16K each. The first bank contains the actual code, the second bank the video mode timings and fonts. Most surprising is the "BIOS size" field in the first bank. I expected to find 16K or 32K there, but it clearly specifies 96K of address space used for the BIOS. At a first glance, this seems like a bug that might cause compatibility issues with mainboards that don't blindly assume that the graphics BIOS does not exceed 32KB. (Basically anything PCI capable)

Yeah, noticed that split banks thing as well. Interestingly the few strings of text in the BIOS don't seem to mention Taxan at all, only Paradise:

22130-A1001
IBM COMPATIBILITY COPYRIGHT PARADISE SYSTEMS, INC. 1986 PEGA BIOS
EGC TABLES&FONTS VER. 1.
(note "EGC")

Evidently it uses 640x400 for text mode as well, since there's an 8x16-dot font for it (which seems to be half "borrowed" from the AT&T PC6300 / Olivetti M24 font... probably because that was a reference 640x400 "standard" when this card was designed):

Would be funny if it turned out to be compatible with "AT&T mode" monochrome software as well.

VileR wrote on 2023-03-30, 18:41:

Yeah, noticed that split banks thing as well. Interestingly the few strings of text in the BIOS don't seem to mention Taxan at all, only Paradise:

Yes, this is obviously a Paradise BIOS, but likely adapted by Taxan.

VileR wrote on 2023-03-30, 18:41:

Would be funny if it turned out to be compatible with "AT&T mode" monochrome software as well.

It is! The BIOS supports the following non-standard modes:

• 40 - 640x400 AT&T mode, 8x16 font
• 48 - 640x400 AT&T-like mode, 8x8 font
• 50 - 640x480 16-color graphics mode (but the sequencer starts with write access to the blue plane blocked. Typo?), 8x14 font
• 51 - 80x30 text mode, 8x16 font
• 52 - 640x400 16-color graphics mode, 8x14 font
• 53 - 80x25 text mode, 8x16 font

Some setting (probably the DIP switch labelled "8-9 DOT") can convert all text 80x25 text modes to 720x400 modes with a 9x16 font (like VGA), but likely slower refresh.

The Taxan EGA card does not support EGA mono operation. It only uses a single DIP switch (probably the DIP switch labelled "EGA-SDY") for monitor/card configuration, which map to the EGA configurations "EGA with EGA monitor and 350-line text mode as primary card, maybe a MDA/Hercules as secondary" and "MDA/Hercules as primare card, EGA with EGA monitor and 350-line text mode as secondary card". Interestingly, the card does not have the 16.257 MHz oscillator required not only for MDA timings (irrelevant, as this card is not designed to drive MDA monitors), but also for standard 21kHZ EGA modes. You can find a lot of pieces in the BIOS that do handle the EGAmono configuration, which is likely generic Paradise OEM code, but I can confidently say that the Taxan variation of this BIOS breaks this feature.

The PEGA2 chip supports software-assisted (but it seems a lot is handled in hardware) legacy emulation using NMI trapping, which is used by the BIOS. If I guess it correctly, it should automatically switch (hence the name autoswitch EGA) between EGA, AT&T-like CGA and Plantronics CGA. The autoswitch functionality seems can likely be disabled using the AUTO SW DIP switch.

• The CGA modes run at standard 15.6kHz/60Hz americant TV timing.
• The 640x350 color EGA modes likely operate at 22.94MHz/29.6 kHz/81Hz
• The 640x400 enhanced CGA modes possibly operate at 22.94MHz/25.15kHz/58Hz
• The 640x400 EGA graphics mode might be broken, as it uses the vertical total register from the 350-line mode
• The 640x480 color EGA modes likely operate at 25.805MHz/31.9kHz/63Hz (close enough that a VGA monitor should sync it, if converted from digital to analog)
• The 720x400 text also might be broken, again due to a bad vertical total setting.

I'm not very confident in these findings, as the 9-dot function with the DIP switch on the card seems to be a signature feature of the card - yet the BIOS parameter table for that mode contains Vtotal=374 scanlines.

mkarcher: very curious findings! Seems like the "EGC" is another AT&T/Olivetti tie-in, since the list of Olivetti video cards includes the "E.G.C. (Enhanced Graphics Colour)" model GO329, which provided 640x400x16 graphics for the M24.

AT&T's version of GO329 was apparently the Display Enhancement Board. The manuals for that one also mention a 640x200x16 mode, and a few 8-color modes which could be overlaid on top of the built-in VDC output (no "16x16 high resolution characters" however).
Since the mode numbers and features are different in the Taxan BIOS (and some of them are apparently broken), I can only guess what they were going for - probably just preliminary support that wasn't developed further...