OAK OTI-037c - 800x600 mode ?

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Re: OAK OTI-037c - 800x600 mode ?

Postby jesolo » 2019-3-27 @ 09:58

There are no jumpers on my card. I guess I could probably test it myself, once I've managed to get an XT PC out of storage
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Re: OAK OTI-037c - 800x600 mode ?

Postby retardware » 2019-3-27 @ 11:04

tayyare wrote:
jesolo wrote:(there might be a jumper to set it up for 16 bit or 8bit)


8-bit capable cards find out this by themselves. No connection of 16-bit ISA part = 8bit.
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Re: OAK OTI-037c - 800x600 mode ?

Postby Deunan » 2019-3-27 @ 14:09

Jo22 wrote:Edit: How about Realtek cards ? Just seen a few online, approx. from the same time period.


Stay well away from any Realtek VGAs. If you think the OAK you have is crappy, you'll find yourself at a loss for words when you test a Realtek. Both performance and video quality are terrible.

I found Trident TVGA8900D to be a good ISA card but it needs to have at least 512kB of VRAM. It will use 8-bit internal bus for 256k, 16-bit for 512k and 32-bit for 1M, although the speed difference between 512k and 1M is not that big, ISA becomes the bottleneck at this point. The output could be better filtered (or maybe its DAC has noise) but it's not bad - even if some people will consider it unacceptable in Doom for example. I also have a VLB Cirrus Logic 5424 and while CL cards have superior video quality in general, my card has some slight vertical pixel crawling in Doom so it's not like these VGAs are perfect. And CL is much more pricey plus I've found the Trident to have better VESA support but that is down to BIOS version/date.
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Re: OAK OTI-037c - 800x600 mode ?

Postby tayyare » 2019-3-27 @ 14:15

retardware wrote:
tayyare wrote:
jesolo wrote:(there might be a jumper to set it up for 16 bit or 8bit)


8-bit capable cards find out this by themselves. No connection of 16-bit ISA part = 8bit.


According to my personal experience with Oak 067 card that I have, that's totally true.

But I see ISA VGA cards with "8bit bus / 16 bit bus" jumpers on them. I'm not sure if those jumpers are for something else entirely, So there is a"might" in the sentence. :blush:
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Re: OAK OTI-037c - 800x600 mode ?

Postby retardware » 2019-3-27 @ 14:52

tayyare wrote:But I see ISA VGA cards with "8bit bus / 16 bit bus" jumpers on them.

Yes you can force them to work in 8-bit mode even when plugged into a 16-bit slot.
(this was explained for maintaining backward compatibility with some esoteric systems)
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Re: OAK OTI-037c - 800x600 mode ?

Postby Jo22 » 2019-3-29 @ 21:28

Hi everyone, just wanted you to know that I got myself an OTI-067 for testing.
It's apparently compatible to the VGAMODE utility of the 37c (it looks the same, at least),
so I'll do some testing next of the CGA and Hercules emulation modes ("Three Shades of Gray" demo on OTI-37c).
I'll also see if I can get the Windows 2.x drivers working on that card (-> thanks Elianda).
jesolo wrote:While going through my "inventory", I also came across one that I have.
Has anyone perhaps tested an OTI-037 based card in an XT PC (i.e., does this 16-bit card work in the 8-bit slot of an XT PC)?

I've seen an 8-Bit 037c card a while ago, so I think the "full" 16-Bit version should work there, too.
What I also wonder is, whether or not such an early chipset would technically work in the other 16-Bit slots of the day.
Namely those based around the 8086 and NEC V30/V40 central processors (Olivetti M24, soviet XTs etc). :)

PS: I also checked FractInt on the 037c. It did all the tweaked VGA modes,
but sadly, the SVGA mode didn't work (got an error message)..
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Re: OAK OTI-037c - 800x600 mode ?

Postby mixerjdp » 2019-3-30 @ 07:45

Jo22 wrote:Hi everyone, just wanted you to know that I got myself an OTI-067 for testing.
It's apparently compatible to the VGAMODE utility of the 37c (it looks the same, at least),
so I'll do some testing next of the CGA and Hercules emulation modes ("Three Shades of Gray" demo on OTI-37c).
I'll also see if I can get the Windows 2.x drivers working on that card (-> thanks Elianda).
jesolo wrote:While going through my "inventory", I also came across one that I have.
Has anyone perhaps tested an OTI-037 based card in an XT PC (i.e., does this 16-bit card work in the 8-bit slot of an XT PC)?

I've seen an 8-Bit 037c card a while ago, so I think the "full" 16-Bit version should work there, too.
What I also wonder is, whether or not such an early chipset would technically work in the other 16-Bit slots of the day.
Namely those based around the 8086 and NEC V30/V40 central processors (Olivetti M24, soviet XTs etc). :)

PS: I also checked FractInt on the 037c. It did all the tweaked VGA modes,
but sadly, the SVGA mode didn't work (got an error message)..


Hello! i have a question: Oti067 works in hercules mode in a monochrome monitor? the specs says that it only emulate MDA (text mode without graphics).
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Re: OAK OTI-037c - 800x600 mode ?

Postby Jo22 » 2019-3-30 @ 14:01

mixerjdp wrote:Hello! i have a question: Oti067 works in hercules mode in a monochrome monitor?
the specs says that it only emulate MDA (text mode without graphics).

Hi, the DIP switchs on the back of the card do select the monitor type, which sometimes is also tied to a specific mode.
On a VGA monitor (maybe EGA monitor, too), several modes are available through the VGAMODE program.
Just select MGA for Hercules. MGA stands for Monochrome Graphics Adapter, in contrast to the text-only Monochrome Display Adapter (MDA).
I suppose they called it that way to avoid being sued by Hercules. A less generic term would be HGC, for Hercules Graphics Card,
Some games and applications of the 80s also say Hercules Monochrome (Card) in their setup programs.

Edit: I don't know the DIP switch settings right now, but you can have a look at stason.org (Tularc category)..
That place has got several drawings of graphics cards, along with these settings bein mentioned.
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Re: OAK OTI-037c - 800x600 mode ?

Postby Jo22 » 2019-4-14 @ 00:24

Quick Update. Just had a little bit of time for testing the 67c..
My guess wasn't so wrong, it seems. The VGA Mode selector program works whit it, as it did with the 037c.
Even more, it has the same glitches in PopCorn. Directly after running VGAMODE, the game is still pinkish.

This leads me to the conclusion, that the CGA emulation ciruit is similar to that of its predecessor.
Here's a little clip that I did a while ago to document that 37c "bug".
https://youtu.be/cu88uKmqlEU

Edit: I also checked the Windows and VBE drivers. VBE driver 67_VESA worked fine, providing VBE 1.1 (?).
The Windows 3.0 driver in 256 col also worked on Windows 3.1, after a bit of work. The Windows 2.x drivers provided 800x600 16col and 1026x768 (in 4col ?).
Unfortunately, they required Windows 286 and 386, in version 2.11. And I've got plain 2.03; non-286, non-386.
The 286 version might have worked, if the driver was written for 2.01 or 2.03 (Win286 is like the plain version, but supports HMA; it can run on XTs, too).

Edir:
tayyare wrote:800 x 600 at 16 colors (4 bit) is ok for 256KB of video RAM

Just double-checked - Yes, seems right. :) Some card's Win 2.x drivers like that of the PVGA or ET4000 even supported 640x400 in 256 colours.
From what I found out, that's also the one and only more-than-16c VESA mode that works with 256KiB of RAM.
I find that kinda funny - 256KiB are the minimum for 256 colours. ^^
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