BMAC PRII 001 Nubus Graphiccard ...

[franklyn]

Looking for some divers to the "BMAC PRII 001" Graphiccard. It has a INMOS IMSG300G-10C Transputer GPU Chip on it and 1MB of VRAM. The EPROM Sticker say "PRISMA II v3.1" ...

There are some sites with MIRO driver on the Web but these are wrong for this card. I can not find something ...

 

[Melkhior]

Just to avoid searching for the wrong thing: the IMS G300 isn't a transputer, it's a "Color Video Controller" (read: video DAC) and would have made a high-resolution device (max 1280x1024 for some). It was made (designed, rather) by INMOS, and manufacturd by SGS Thomson. So don't expect acceleration on this one, I don't see any chip to do that. And the hardware cursor wasn't usable in MacOS, shame on Apple.

Actual transputers were CPU, and can be found on NuBus, but as parallel acceleration device, not graphic/video.

 

[zigzagjoe]

That's not an accelerated video card, depending on what version of Mac OS they were targeting they may not have even had an extension for it.

Check in the monitors control panel, hold the option key and click the options button. If you see a list of resolutions then no additional software is needed; pick a new resolution, reboot and it ought to change.

 

[franklyn]

I plugged the card into my Quadra 700, and the occupied Nubus slot doesn't appear in TattleTech. Now I have to measure the card's 9-pin VGA connector first ...

With so few pins on the 9-pin connector, surely there's no way to detect whether a monitor is connected to the card or not?


VGA Standard 9pin
1 - Red
2 - Green
3 - Blue
4 - V Sync
5 - H Sync

6 - Red GND
7 - Green GND
8 - Blue GND
9 - GND

 

[cheesestraws]

what do you mean by 9 pin standard VGA? There is no such thing.

 

[lobust]

With so few pins on the 9-pin connector, surely there's no way to detect whether a monitor is connected to the card or not?

Not exactly the same card, but this suggests otherwise:

miroGraph Chroma v3.3a

Some info on the miroGraph Chroma v3.3a NuBus video adapter.

longview.be

 

[Bolle]

There are no drivers needed for that card. The INMOS chip is indeed not a Transputer but a simple RAMDAC.
The card will not show up if there is not monitor connected. One of the pins on the 9pin connector is directly wired to the enable signal on the ROM and needs to be grounded, otherwise the card will be invisible to the Mac.

miroGraph Chroma v3.3a​

Some info on the miroGraph Chroma v3.3a NuBus video adapter. longview.be

The pinout specified here does also apply to OPs card. I've got all variants of those 4/8/16bit Miro Nubus cards and they all work with the same adapter I built.

 

[franklyn]

I'm a little confused. I don't want to modify the card like the instructions suggest. What would be the right VGA adapter without any modification?

1 - Red
2 - Green
3 - Blue
4 - n.c
5 - H sync
6 - GND
7 - GND
8 - GND
9 - V Sync

 

[Bolle]

The pinout of the unmodified card is:

1 - R
2 - G (with SoG)
3 - B
4 - Csync
5 - 12V through resistor or nc. (resistor not present on your card)
6 - Ground
7 - ROM_OE (this needs to be shorted to ground)
8 - Ground
9 - 12V or nc.

So the easiest way to connect this to a monitor is using pins 1, 2, 3 and the two grounds on pins 6 and 8 and build your adapter so it shorts pin 7 to one of the neighboring ground pins.

 

[franklyn]

I try it and make a Adapter ...

1 - RED
2 - GREEN
3 - Blue
4 -
5 -
6 - GND
7 - GND
8 - GND
9 -

... I test two Monitor a NEC MultiSync LCD1970NX and a MIRO LCD Model 568 but I don't get a picture via the MIRO graphics card.

It do not work without any sync I think?

 

[franklyn]

GPU Pinout ...

 

[franklyn]

Pin4 = 5V
Pin5 = 0V
Pin9 = 0V

... have I connect Pin4 ?

 

[franklyn]

There is a LM1881N to convert C Sync to H Sync and V Sync ...

 

[luRaichu]

If your monitor supports Sync on Green, a C Sync splitter isn't needed.

 

[franklyn]

I think the NEC Multisync supported sync on green but the Display say "no signal". I also use a ijyama or a Miro Display.

 

[franklyn]

V Sync (GPU-A6) -> 74F241 Pin8 (IN)
C/H Sync GPU-C6) -> VGA socket Pin4

... a LM1881N is the only way?

 

[franklyn]

I tried connecting the C/H sync as Hsync and the Vsync directly from the GPU pin A6 as Vsync. Of course, it doesn't work.

Can't you tell the GPU to only output Hsync instead of outputting C/H sync via pin C6? I think there's an Atari VME bus graphics card with the same chip, and that works with normal Hsync and Vsync.

 

[franklyn]

The pinout of the unmodified card is:

1 - R
2 - G (with SoG)
3 - B
4 - Csync
5 - 12V through resistor or nc. (resistor not present on your card)
6 - Ground
7 - ROM_OE (this needs to be shorted to ground)
8 - Ground
9 - 12V or nc.

So the easiest way to connect this to a monitor is using pins 1, 2, 3 and the two grounds on pins 6 and 8 and build your adapter so it shorts pin 7 to one of the neighboring ground pins.

@Bolle ... did you modify your adapter by adding Sync on Green via a transistor? My NEC monitor supports SoG, but it doesn't display a picture and indicates it's not receiving any signal, so I suspect my card doesn't have SoG. I can see the card's desktop in the monitor control panel.

 

[franklyn]

The card is faulty.