I have discovered how to improve ATA/IDE CD-ROM performance under Win95 after many moons of searching RegEdit and experimenting.
Under the System Properties/Perforrnance/ File System/CD-ROM tab, you'll find the "Supplemental Cache" and "Quad Speed or Higher" settings. Win95 sets the cache at a miserly 1,238K maximum and the CD-ROM optimize speed at 4x. There's no "higher" about it, as you'll see. So, how do I optimize for my 8x CD-ROM drive?
Open RegEdit and chase down the HKey_- Local_Machine\System\CurrentControlSet\ Control\FileSystem\CDFS key. Wnte down the numbers for "CacheSize" and "Prefetch," in case you want to restore settings. (Leave Prefetch Tail" alone. I played with this and actually slowed down the CD-ROM).
Double-click the CacheSize entry, and Edit DWord will open. Switch to Decimal. It should be displaying 619 or 617, or some such, in the window (I've found three different numbers). I tripled my number to 2,476, which gives you a 4,952K cache. You can go higher.
Now open PreFetch and switch to Decimal. The number displayed, 228, represents the "Quad Speed or higher" setting. Each time you add 56 or 58 to 228, you jump your optimize speed up by 2x. 1 use 347 for my 8x drive. but 340 works iu drive, but 340 works just as well. Close RegEdit and reboot for the settings to take effect.
You can experiment with a little CD-ROM overclocking here. I was up to 13x with no problems. There will be a ceiling for speed gains, and each type of CD-ROM drive will perform differently depending on how it utilizes the higher settings. Iust make sure you write down your original numbers and keep track of your settings.
Run your benchmarks. In SiSoft, the CD-ROM Index is 800 for an 8x drive and 1,200 for a 12x. Mine now clocks in at 920. Variables such as the types of CD-ROM drives and discs used, and the usual ups and downs of IDE CD-ROM reads and writes and buffers, can make the marks vary. But I'm happy with the way my drive is performing. --Vern Earlywine
Contributing Writer Sean Downey replies: The settings Vern describes are related to Window's CD-ROM cache. Win95/98 uses a data cache to buffer CD data streams and decrease seek latency. The separate keys control the overall cache size and the size of the cache used to store path table, directory, andfle information. We tested Vern s tweaks with some interesting results.
On some systems, the CacheSize and Prefetch keys are binary values instead of DWORD. rn this case, you can determine the decimal values by creating a new DWORD value and entering the hexadecimal data stored in each key in reverse order as the DWORD hexadecimal value. 7hen switch it to a decimal value within the edit DWORD value box. You can use the same method to determine the hexadecimal values of the new settings.
In our tests, increasing the cache size helped the playback oftest AVls, but didn't do much to of test AVls, but didn 't do much to increase game performance. For most games, it's more important to fork over as much memory as possible since they do a much betterjob of predicting their own resource needs than Windows. We did, however, achieve excellent results by bumping up the Prefetch value