The most important new feature of my new motherboard tests is certainly the compatibility testing. To do this I tried to be as nasty as I could, making a successful pass as difficult as possible. This test shall reflect situations which come close to what my readers could see in their own system after plugging a new add-on card in their system.
Card Compatibility Test 1
The first and most important test shows the following situation:
I decided that a modern system should not only run with an AGP graphics card, but also with a Voodoo2 3D add-on card. This is not asked too much, since the Voodoo2 cards don't require an own interrupt and only some mapped memory area which should be easy to supply. I also expect a PCI UW SCSI card to run in this system and I used the pretty common Adaptec 2940UW SCSI host adapter, but also the DPT PM-2144UW and the Tekram DC-390F. All cards showed the same, they either ran all or none of them did. Additionally to this I used a cheap PCI network adapter which you can get for $30 to $40. The used card is the Realtek RTL8029 PCI card, which is just fine for the usage in multiplayer gaming and some basic file transferring. To be really nasty I also used an old Soundblaster16 ISA legacy card, which does not do PnP.
Hence the system had to host five components at the same time:
- an AGP graphics card, the Canopus Total3D 128V AGP in the AGP slot
- a 3Dfx Voodoo2 add-on 3D card, the Creative 3D Blaster Voodoo2 in the PCI slot next to the AGP slot, which usually is PCI Slot #1 unless it's a Supermicro board that counts the other way around.
- a PCI UW SCSI host adapter, either the Adaptec 2940UW PCI or an onboard SCSI adapter if available in the second next PCI slot after the AGP slot, usually #2
- a PCI LAN adapter, either the Realtek RTL8029 or an onboard LAN adapter in the third, usually #3
- an ISA sound card, either the Creative Soundblaster16 ISA legacy or an onboard sound device in any ISA slot, there's no difference
The device were plugged into the board in the following succession:
- AGP graphic
These five devices were supposed to run all without any problems, which means that you had to be able to use the RIVA's 3D features, the Voodoo2's 3D features, a SCSI hard drive had to run at acceptable speed, I had to be able to connect to my network and the sound card was supposed to play sound. The Windows 95 system manager was not supposed to report any problems.
On top of that I expected COM1, COM2 and LPT1 to work properly as well as both EIDE ports, running an EIDE hard drive on the one port and a IDE CD-ROM at the other.
This may sound tough, but it should certainly be possible as you can see in this list:
- COM1 taking IRQ4
- COM2 taking IRQ3
- LPT1 taking IRQ7
- Soundblaster16 taking IRQ5
- primary IDE port taking IRQ14
- secondary IDE port taking IRQ15
- AGP graphics card taking IRQ9-11
- SCSI adapter taking IRQ9-11
- network adapter taking IRQ9-11
As you can see, there are definitely enough IRQ's available, the AGP, SCSI and network card only have to distribute IRQ9, IRQ10 and IRQ11 amongst each other properly and everything would run fine. There is one problem though. Since the RIVA doesn't like sharing its IRQ with any device and the SCSI and network cards don't work with IRQ sharing either, there wasn't any IRQ available for the USB anymore. Thus the board ran into trouble if the USB IRQ could not be disabled. In case of the Award BIOS, IRQ5 had to be declared 'ISA legacy', so that it wouldn't be distributed amongst the cards that are asking for an IRQ. This was not counted as a test failure, because the Soundblaster16 is an ISA legacy card indeed. Only the Siemens D1064 didn't require this procedure.