OAK OTI-077 VGA card in a Tandy 1000: VGAMODE.EXE legacy emulation issues

[Eudimorphodon]

This is kind of a far-out one, but maybe someone has a similar config.

I recently stuffed an OAK OTI-077 VGA card in a Tandy 1000 HX via an ISA slot adapter. The OTI-077 has a 16 bit connector but it only has an 8-bit wide BIOS and it seems to otherwise work fine in an 8-bit slot; the Tandy BIOS recognizes it and disables the built-in video as expected, and testing several games, GEOworks, and Windows 2.11 in EGA and VGA modes has all gone relatively smoothly, so I'd say the card basically works.

The one thing I've run into: I had an Oak VGA card many, many moons ago (my first VGA card in a 286 machine back around 1989-ish was an OAK) and I recalled that those cards had a utility which could make it "fake" several legacy cards at a more register-compatible level. (The main use for it back then was to allow games that used the hacked 160x100 CGA "graphics mode", like Round42, to run. Rarely it could also come in handy for faking having a Hercules card.) I tracked down a .zip file of drivers called "OAK-077.ZIP", and in it was a "VGAMODE" utility that offers similar functionality on this card...

The problem is that running this program to set any of the legacy modes results in a hard crash. (It can set extended 132 column text modes, etc, all right.) Wondering if anyone has a similar OAK card in an older Tandy 1000 (SX/TX-era ideally) and has a similar inability to use the legacy emulation. Mostly just curious if this is a unique problem with the HX (Which obviously is about as far from a standard configuration as you can get) or a general Tandy 1000 problem.

Alas I *don't* have a conventional ISA slotted PC to try the VGA card in to absolutely confirm it works there, it is of course possible I have the wrong utility for this exact card. The only reason I know it's an "OTI-077" is a sticker on the BIOS chip, there's no other obvious branding. Card has a single jumper which I think is for setting "VESA mode", that's currently disabled.

 

[keenerb]

This is kind of a far-out one, but maybe someone has a similar config.

I recently stuffed an OAK OTI-077 VGA card in a Tandy 1000 HX via an ISA slot adapter. The OTI-077 has a 16 bit connector but it only has an 8-bit wide BIOS and it seems to otherwise work fine in an 8-bit slot; the Tandy BIOS recognizes it and disables the built-in video as expected, and testing several games, GEOworks, and Windows 2.11 in EGA and VGA modes has all gone relatively smoothly, so I'd say the card basically works.

The one thing I've run into: I had an Oak VGA card many, many moons ago (my first VGA card in a 286 machine back around 1989-ish was an OAK) and I recalled that those cards had a utility which could make it "fake" several legacy cards at a more register-compatible level. (The main use for it back then was to allow games that used the hacked 160x100 CGA "graphics mode", like Round42, to run. Rarely it could also come in handy for faking having a Hercules card.) I tracked down a .zip file of drivers called "OAK-077.ZIP", and in it was a "VGAMODE" utility that offers similar functionality on this card...

The problem is that running this program to set any of the legacy modes results in a hard crash. (It can set extended 132 column text modes, etc, all right.) Wondering if anyone has a similar OAK card in an older Tandy 1000 (SX/TX-era ideally) and has a similar inability to use the legacy emulation. Mostly just curious if this is a unique problem with the HX (Which obviously is about as far from a standard configuration as you can get) or a general Tandy 1000 problem.

Alas I *don't* have a conventional ISA slotted PC to try the VGA card in to absolutely confirm it works there, it is of course possible I have the wrong utility for this exact card. The only reason I know it's an "OTI-077" is a sticker on the BIOS chip, there's no other obvious branding. Card has a single jumper which I think is for setting "VESA mode", that's currently disabled.

Don't forget there's a utility that will switch between the built-in video and VGA on 1000 systems as I recall; perhaps that will also work on the HX.

 

[Eudimorphodon]

Don't forget there's a utility that will switch between the built-in video and VGA on 1000 systems as I recall; perhaps that will also work on the HX.

I'll look for that. I did find some references to another utility, "vgafix.zip", that's recommended on 1000s with VGA cards to fix some defective behavior in setting up the BIOS data area; that probably explains a couple instances I've seen of programs not reliably detecting the video type.

Still curious, though, if the "legacy mode" on cards like this OAK works for anyone else. I am wondering if it may well be clashing somehow with the built-in video registers even when they're in "disabled" mode; if that were the case then I'd expect the same on at least any "Big Blue 1"-equipped Tandy. (EX/SX/HX/TX; maaaybe not on the SL/TL family, as they use a slightly different version of Big Blue?)

 

[Eudimorphodon]

I'll look for that.

Found Vswitch, alas I'm not too optimistic it'll work on an 8088-based Tandy 1000. It was written specifically for a 768k TL, and the 768k 286 Tandy machines don't share their video memory with the CPU to backfill the under 640k mark. Without some hacking to have it reset the top of memory appropriately I suspect bad things will happen. Maaaybe stacking it with adjmem?

One of the things that makes me wish I had even marginal skill in 8088 machine language is I think it might be technically possible to patch the memory detection and video initialization routines of the EX/HX/SX with that from the TX so they could also run in the "768k" mode if fitted with a suitable memory card. Unfortunately the software side of that is well above my current skillset. (I could probably hack together the *hardware* to try it by piggybacking another RAM IC on my memory board. Could also use something like a lo-tech memory card in a more conventional Tandy like an SX.)

 

[Eudimorphodon]

... and yeah, had to try it. VSWITCH results in an earth-shattering kaboom. (Well, okay, a freeze.) Maybe it'd be possible by combining code between it and adjmem to hack something together that works on the 808x machines, but it doesn't work now, at least for me. (If it works for someone else that'd be interesting...) VGAFIX does seem to be working to fix VGA detection issues.

 

[jasa1063]

Despite VSwitch not working, congrats on getting the VGA card to work in a Tandy 1000 HX. I am always amazed at how people keep enhancing those nifty all-in-one Tandy 1000s!

 

[Eudimorphodon]

Despite VSwitch not working, congrats on getting the VGA card to work in a Tandy 1000 HX. I am always amazed at how people keep enhancing those nifty all-in-one Tandy 1000s!

Thanks. I like to think at this point my HX at least ranks pretty high among the more ridiculously tweaked-out builds out there. To go any further I'm either going to need to make some more multi-function cards or add a multi-slot riser...

Mentioning VGAFIX again, another problem it solves is with Topbench. Without it installed Topbench was unable to reliably identify the video type and it just spat out a stream of garbage in the "VideoAdapter" section. With it installed it says "VGAOAK OTI-077, 1024kb video memory". Apparently it really is indispensable for an upgraded 1000.

 

[Agent Orange]

Thanks. I like to think at this point my HX at least ranks pretty high among the more ridiculously tweaked-out builds out there. To go any further I'm either going to need to make some more multi-function cards or add a multi-slot riser...

Mentioning VGAFIX again, another problem it solves is with Topbench. Without it installed Topbench was unable to reliably identify the video type and it just spat out a stream of garbage in the "VideoAdapter" section. With it installed it says "VGAOAK OTI-077, 1024kb video memory". Apparently it really is indispensable for an upgraded 1000.

I have an Oak 8-bit VGA (640 x 480) in my 1000SX. One needs to only flip the SX SW1 dip switch to 'off' in order to access the video card - no additional files needed. The card presently drives a 15" Dell LCD. I have no clue as to how the 1000SX relates to 1000HX's VGA setup, however. Prior to the Oak card, it had an EGA with a CRT monitor and the presentation was outstanding for its time; all the way back to 1988.

 

[Eudimorphodon]

I have an Oak 8-bit VGA (640 x 480) in my 1000SX. One needs to only flip the SX SW1 dip switch to 'off' in order to access the video card - no additional files needed.

The TX and SX have that switch, but the HX's bios automatically detects a VGA card, there's no switch needed. The "VGAFIX" thing just covers up some warts that are apparently present in all Tandy 1000s after they're upgraded with one. (They don't update the BIOS data area correctly. Most things work anyway, it just breaks some attempts at autoconfiguration. You likely wouldn't notice if you just told anything that needed configuration you had a VGA card.) If you want to try to reproduce some of the things VGAFIX fixed and see if they apply to you.

1: The game Paku Paku's screen aspect ratio is messed up without it.

2: Topbench couldn't identify the BIOS signature of the VGA card in the "add to database" function (or when running Topbstub) and was unsure of video type.

3: The game "Magiduck" thinks the computer has MCGA and likewise starts with a messed-up aspect ratio.

4: Cutemouse 2.1 doesn't detect EGA/VGA. (On CGA cards Cutemouse produces a "No VGA? ..." message on initialization, it did that with the VGA card installed as well unless vgafix was installed.)

5: Several other installers made bad guesses about installed video type. (Windows 2 guessed "Hercules", GEOS guessed EGA Monochrome. Both worked fine when configured specifically for VGA.)

Whether it's *actually* needed for sure might depend on the particular VGA card. According to the docs for VGAFIX apparently these detection problems applied to a Paradise card that Tandy actually sold in their stores for the 1000SX/TX.

If your OAK card does have the VGAMODE program or equivalent to enable the CGA/Hercules register compatibility modes I would be very interested to know if they do work on the SX, or if they also cause problems.

(I'm *pretty sure* my aaaancient 256k OAK that had dip switches and a digital port came with a program to flip on the legacy emulations, which you could also set with the DIP switch, but I don't know the name of it.)

 

[Agent Orange]

If your OAK card does have the VGAMODE program or equivalent to enable the CGA/Hercules register compatibility modes I would be very interested to know if they do work on the SX, or if they also cause problems.

My SX is on the shelf at this moment as I have other 'projects' taking up precious space. I was planning on a dust off fairly soon, so I'll be able to crack it open and see what's what. I may have another OAK that I can get to and I'll see what's up with it.

 

[Agent Orange]

I located my 16-bit Oak video card but it'a not for the 1000SX, however, it might work. I don't have the manual but the 2 jumpers; i.e. JP 2 & JP 3 seem to be for Mono/Color and Interlace/Non-interlace.

View attachment 62362

OTIVGA 1570
OTI077 512 K ISA 16 BIT VGA

 

[Eudimorphodon]

That card sounds like it's a very close relation to the one I have in my HX. Looks like they made a ton of only slightly-different 077 based cards that only differ in how much RAM is installed and how many jumpers they have.

 

[Agent Orange]

That card sounds like it's a very close relation to the one I have in my HX. Looks like they made a ton of only slightly-different 077 based cards that only differ in how much RAM is installed and how many jumpers they have.

It looks to be 512 K with 2 jumpers. Some of those early Oak VGA cards were selectable between 800 x 600 & 1024 x 768 or some variation.

 

[Eudimorphodon]

If the vague documentation out there is to be taken at its word the jumpers primarily affect the refresh rate of certain SVGA modes, they effectively don't do anything if you're just using it as a plain VGA card.

The "VGAMODE" utility that sets up the legacy modes is hidden inside the "OTI-077.ZIP" file at this FTP site:

ftp://retronn.de/driver/oak/

Strangely it's inside a "utilities.zip" that's inside the parent zip. Setting VGA text/graphics modes with it works fine, trying to use the emulation switches, "VGAMODE C", "M", or "E", boom, a crash from which CTRL-ALT-DEL will not recover from.