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PC Compatibility Card in G4 MDD

greystash

Well-known member
I managed to get a PC Compatibility card (PCI) for $20 (unsure of the exact details of it, it's either 100Mhz or 160Mhz). I installed it in my MDD because I no longer have any early PPC machines with PCI and it mostly works. The PC card boots and runs, can switch to and from the system and the only issue is that it causes the system to crash when I shut down the Mac system. When switching to the PC side the Mac screen dims but I get no PC output because I don't have the video loopback setup.

My question: If I get an adapter for the video out can this port display the video for the PC side to another monitor/cable? I can't install a loopback cable and there's no GIMO slot so it can't be routed to the MDD video/existing PCI video card. The PC card has a different video connector to the early PPC machines (DB15?). Am I correct in saying this connector may be a 26-pin D-sub (DA-26)? If so could I get a DA-26 to VGA/DVI adapter to use for video output?
 

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jeremywork

Well-known member
Excellent score for $20! and nice to know these work all the way up to the end of the line.

I believe that's a 100MHz model, as the 166 ones I've seen have two VRAM chips soldered where the 100s usually have upgradeable sockets.

The DA-26 cable is designed for this adapter
PCCardCable.gif
If combined with the relatively common VGA-M to DA-15-F adapter commonly shipped with PowerBooks (590-0322-A)
GeorgeGTS_6_1329031422.jpg
and of course, another adapter to get back to VGA, you can use the loopback function with the G4 without issue.

If you only want to run a separate display for the PC, a custom adapter which skips the input signals should work. The manual for this card (or the predecessor or its third party cousin, can't recall) even mentions leaving the loopback portion unhooked as a valid configuration for two-monitor use.

The pinout for the 3-way cable is here, but be sure to note the 4-way cable is for the earlier cards and won't work for this one:
 

greystash

Well-known member
Thanks I thought so too, I can't believe nobody else bid on it!

Oh nice thanks that's good to know, I'll have to see if I can source the VRAM chips from somewhere.

That's very interesting!! Thank you so much for pointing me in the right direction, I've bought the parts and will attempt to build my own cable. I can't wait to have it going!

Thanks again @jeremywork !
 

jessenator

Well-known member
I believe that's a 100MHz model, as the 166 ones I've seen have two VRAM chips soldered where the 100s usually have upgradeable sockets.
And 166s have DRAM soldered on the back side as well (bottom) vs 100 (top)
sHp5IyCh.jpg


Also, the (Cyrix) 166-C may or may not have socketed VRAM, because I've never managed to find so much as a picture of one, save an eBay listing (which also may or may not have been one…ugh). The Apple Memory Guide shows an illustration with sockets, but some of those diagrams aren't completely correct : /
vnbXK9hh.png
 

greystash

Well-known member
That's interesting, I didn't actually know these variations existed until I found this card.

Thanks for the info @jessenator! I'll have to keep an eye out for a 166 card, they sound like a bit of an upgrade.
 

greystash

Well-known member
After ordering parts to make a cable I managed to get both variations of the cable for $15! I can't get the loopback function working since I need a VGA (male) to DB15 (female) adapter. After booting the PC I unplugged the monitor cable from my video card, and with an adapter connected it to the PC video cable. I was able to get this output but it's all garbled.

Hitting any key returns/duplicates whatever error message is being displayed in the lower blocks of text. Pressing ctrl + alt + delete will reboot the PC.

Any idea what would cause this? Could dodgy capacitors result in this sort of effect?
 

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Last edited:

jeremywork

Well-known member
After ordering parts to make a cable I managed to get both variations of the cable for $15! I can't get the loopback function working since I need a VGA (male) to DB15 (female) adapter. After booting the PC I unplugged the monitor cable from my video card, and with an adapter connected it to the PC video cable. I was able to get this output but it's all garbled.

Hitting any key returns/duplicates whatever error message is being displayed in the lower blocks of text. Pressing ctrl + alt + delete will reboot the PC.

Any idea what would cause this? Could dodgy capacitors result in this sort of effect?
It might be worth checking what the display preference is set to in the PC Setup control panel on the Mac side. If nothing is connected while the DOS machine POSTs it could end up in an unsupported mode.
 

greystash

Well-known member
It might be worth checking what the display preference is set to in the PC Setup control panel on the Mac side. If nothing is connected while the DOS machine POSTs it could end up in an unsupported mode.
Having a monitor connected before it boots doesn't seem to make much difference unfortunately. I've just tried with two monitors, and have gone through each monitor setting within the control panel and got the same results (except for the unsupported resolutions e.g. portrait). If I choose auto sense it will select the Multiscan 17"
 

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AeSix

Active member
I also tried using a different VGA adapter and went through a bunch of dip switch settings as mentioned here, but it didn't make any difference.
I know I'm 8 months late to the party here... The corruption in the images of the DOS side booting up, does not look like wrong monitor settings or any such thing. I've seen older /real/ 486 hardware do this as well. Turned out to be short circuits from dust or such. Some aerosol electronics cleaner fixed it for me. However, I've also seen where the BIOS on a Pentium 4 machine was corrupted, causing similar output to the screen.
 

Amstradcpc

New member
Hi, I've installed a pc dos card 7" into my MDD tower also and it works well via vga monitor.
The only problem is I am unable to install dos 6.2.2 because i don't have a floppy drive (usb floppy doesn't work - tried this) so looking around to see if anyone has a pc drive file already loaded or is there a trick way of doing it?

Also, yes - os9 crashes when trying to shut down/restart same as original poster stated.
 

lolo799

Active member
I'm not sure about the rules for sharing copyrighted contents so check your PM.

Interestingly enough, an older version of the control panel, from Reply, can display diagnostics and information about the card, but it works with PDS cards only.
 
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