In a nutshell: CPU Galaxy is reportedly making ready to host a problem wherein individuals should get Doom to run at a mean of 25 frames per second utilizing an ISA card. That’s no simple activity however no less than one YouTuber was as much as the check and received an early begin on the competitors.
As Mike from vswitchzero notes, the principles prohibit using “newer” boards with PCI slots however you should use any CPU you would like as long as it adheres to the opposite tips. The sport, in the meantime, have to be run in prime quality graphics mode with the viewable space expanded all the way in which to the HUD. Phil’s DOS Benchmark Pack was used to run the proper demo file.
Mike’s check bench is constructed round an MSI MS-4138, a 5v-only motherboard with stable compatibility that can also be fairly tweakable. Additionally alongside for the journey is a 60-ns RAM module (eight megabytes), an ATI Mach32 graphics card, and an Evergreen improve processor primarily based on the AMD Am5x86. Mike went with this CPU resulting from its entrance facet bus flexibility.
Leaping proper in, he left the entrance facet bus set to 33 MHz however modified the ISA divider to 1/3 for an 11 MHz clock (up from 8.3 megahertz). Oddly sufficient, there was no efficiency improve when operating the Doom benchmark and upon additional inspection, it appeared as if a BIOS bug was accountable. One not-so-quick flash to a more moderen beta BIOS later, and he was again in enterprise.
Retrying the 1/3 divider for an 11 MHz ISA bus clock, the Doom benchmark spit out a mean of 21.9 frames per second. To essentially push the ISA bus, nonetheless, Mike wanted to up the entrance facet bus. He elevated the FSB to 50 MHz and set the multiplier to 3x for a 150 MHz CPU clock, solely having to barely loosen up the cache write cycle to 2T for stability functions.
With these settings and a 12.5 MHz ISA clock, he was capable of hit a mean of 25.1 frames per second within the Doom benchmark. Mission achieved. With two different dividers to strive, nonetheless, the journey was removed from over.
Associated studying: Modder provides ISA slot to trendy PC for retro gaming goodness
Again within the BIOS, Mike set the FSB divider to 1/3 for a 16.67 MHz ISA clock. That may be a full one hundred pc overclock of the ISA bus however remarkably, the system took it like a champ. Doom ran at a mean of 30.4 frames per second with no graphics anomalies. All that was left was to strive the 1/2 divider for a 25 MHz ISA clock. Extremely, it labored simply tremendous and he was capable of full the Doom benchmark at a mean of 35.7 frames per second.
Mike experimented with a few totally different {hardware} configurations and different functions however stability points crept in. Nonetheless, it’s enjoyable to see what’s doable with legacy {hardware} when actually pushing the envelope.
