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- Document PIT access modes, channels and operating modes. - Rewrite HalHandleNMI to use the System Control Port definitions instead of magic values that were never explained. - Rewrite HalMakeBeep not to program the PIT with magic hexadecimal values that were not explained anywhere and seem dubious. - Fix the PIT frequency to match its correct value of ~1.19318MHz which is what every x86 book states and what Linux and all other operating systems use. This is equivalent to one third of the NTSC color burst (subcarrier frequency) used on CGA computers for video output. Previously, the HAL used 1.193167MHz, which is only used by NT and isn't documented anywhere, and in fact appears to be a typo in the NT sources (a less accurate way of dividing the NTSC color burst gives 1.19318167MHz). Somehow, the ReactOS developer of this function must have made the same "typo", by complete coincidence, of course. - Rewrite part of HalpInitializeClock to use the new definitions. This function was at least somewhat documenting the magic values. svn path=/trunk/; revision=44991 |
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