On Mon, 1 Nov 2004, Eric Auer wrote: > That "PMIDX" structure is followed by 9 "selector" (?) words, > and you can replace the a000, b000, b800 and c000 ones to tell > the BIOS that it has to use other segment values to access VGA RAM, > mono text RAM, color text RAM and itself, respectively. > The BIOS is even checking if CS is c000 when you enter it, and if not: > 0x887: push DS DS=CS SI=0 CLI CLD MOVSD_0x4000_DWORDS pop DS > (ES:DI is a000:0 at that moment, NOT using the replaceable a000 from PMIDX) > Otherwise, it does:
[...] > Does anybody have experiences with that PMIDX or cc33cc3300000000aa55aa5500000000 > "protected mode BIOS module" header described above? Would be interesting > to know. After all, there are far more things happening than creeping > around in the first 1 MB in modern computers. Hi Eric, http://www.vesa.org/vbe3.pdf specifies a protected mode interface, that's probably what you see here. Essentially VBE2.0 provides a few 32 bit hooks to do fast bank switching, palette switching and hardware scrolling in protected mode. VBE3.0 optionally offers 16 bit protected mode hooks into the BIOS; then the BIOS code is written in such a way that it can work in both 16 bit protected mode and in V86/real mode. The Linux kernel also uses some protected mode BIOS interfaces, for instance for APM, and also the VBE 2.0 stuff if you use the VESA framebuffer on the console. Bart ------------------------------------------------------- This SF.Net email is sponsored by: Sybase ASE Linux Express Edition - download now for FREE LinuxWorld Reader's Choice Award Winner for best database on Linux. http://ads.osdn.com/?ad_id=5588&alloc_id=12065&op=click _______________________________________________ Freedos-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/freedos-devel
