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optimizing performances *
> Freeing up IRQs
If you plan on adding a bunch of cards into your system, you most likely will run out of available IRQs. It seems that every device wants one, yet we only have 16 available, up to 12 of which are stolen by the motherboard. So how do you free up IRQs if you need more? What do you do if you plug in that shiny new PCI sound card, only to find out that it demands 2 IRQs and you only have one left?
One thing to do is to disable, in the BIOS, devices that are integrated on to the motherboard but aren't being used. I know a lot of you are using a PS/2 mouse, which hogs an IRQ. That's fine, but did you know that you probably have two unused COM ports that are each using an IRQ? Simply go into the BIOS and change the settings for these COM ports to disabled, and you will have two more IRQs up for grab.
Other things to ask yourself, regarding freeing up IRQs: Are you using USB? How about the PS/2 mouse port? The printer port? What about the Secondary IDE channel, or even the Primary if you use SCSI? Heck, maybe you're way out there and don't have any floppy disk drives, leaving the motherboard port unused. All these can be disable in the BIOS, freeing up an IRQ. The printer port would even free up a DMA channel, but luckily those aren't in heavy demand. Take note that Windows 95/98 doesn't always detect the changes made in the BIOS, so your best bet after making the BIOS tweak is to reboot and then run the Add New Hardware Wizard in the Control Panel. This way you can be sure that everything is accounted for, as the wizard not only detects new hardware but also detects hardware that has been removed. If it still doesn't see the changes, go remove each item manually from the Device Manager, reboot, and then run the Add New Hardware Wizard once more just to make sure. If Windows starts adding everything back in, and you're absolutely sure you have them disabled in the BIOS, well then you're just SOL.
One last thing to check is if you have an option in the BIOS along the lines of "Enable IRQ for Video." Some video cards don't really need an IRQ, while other, higher performance video cards do need one or they will behave irregularly. If you are in desperate need of an IRQ, try disabling this. Just be sure to switch it back on if you notice anything wrong.
> Boosting the Pentium Pro/Pentium II video chipset
Pentium Pro and Pentium II chipsets have some special performance enhancing features, namely fast video access. Pentium II's already have most of these options enabled, while older Pentium Pro chipsets have these turned off for stability reasons. Obviously, you want to enable these! The difference in video performance, especially with Pentium Pros, is enormous. To enable those features, go to http://www.fastgraphics.com/ and download FastVid. Installation of this program is fairly simple, however you must make certain that you run it in the same directory that you extract DOS4GW.EXE to. For example, in my AUTOEXEC.BAT, I have the following lines to load FastVid:
cd c:\utility
FASTVID 111 -2 dc000000
cd c:\That changes to the directory that FASTVID.EXE and DOS4GW.EXE are located, loads it in to memory, then changes back to the root directory and finishes up with everything else. Your settings will be different based on your video card.
Pentium Pros will see a bigger difference in video performance when compared to a Pentium II's increase in performance. Here are some benchmark results using DOS Quake, on a Pentium II 333 (83x4 as opposed to 66x5.0) with a 2MB Diamond Stealth 3D 2000 on an Asus P2B motherboard:
Resolution Without FastVid installed FastVid installed 320x200 Mode 13h 68.5fps 71.0fps 320x200 VESA 2.0 77.8fps 79.5fps 640x480 VESA 2.0 41.4fps 42.0fps 800x600 VESA 2.0 36.8fps 37.3fps Not a big difference, but it's there.
> No ISA cards = 5% performance boost
Not having any ISA expansion cards in your system can boost performance by about 5%, at least for older Socket 7 based systems. I haven't quite confirmed that there is a performance boost for Pentium II or Pentium Pro based systems, although there does to seem to be a small boost, as Norton System Information scores went from 160.8 to 161.5 on the Pentium II 333 system. On an older 200MHz AMD K6 (overclocked to 225) with a 4MB 3Dfx Voodoo card, framerates jumped from 22.5 to 24.1fps in Quake 2, a difference of 7.1%, when the modem was removed. The system was equipped with a Diamond Monster Sound to handle audio.
I don't know that you should go ripping out all your ISA cards and buying newer, more expensive replacements (external modem, PCI sound card), but when you upgrade you should consider planning on having an ISA free system if you can.
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