Eric Auer <[EMAIL PROTECTED]> writes: > Hi Pat, your patches and/or MEMDISK have the problem that they do > not DETECT which A20 setting styles work and which not! > > - PS/2: port 92h -> or 2 to enable, and ~2 to disable A20 > - 8042: command d1 / port 60 ... here, too, ONLY bit 1 should be messed > with (or 2 / and ~2). It is important to do "wait until 8042 is ready" > and "wait until A20 actually switched". 8042 is slow! > - BIOS: your BIOS call may or may not function, depending on the BIOS. > > So you should try PS/2 first. If this does not work, try BIOS. Finally, > try 8042.
The BIOS authors know better than anybody how to handle the A20 gate on their hardware. So I think we should always try the BIOS first. In other words, I think the order used by memdisk is correct: First try BIOS, then 8042, then PS/2 (aka. 92h gate). > Then keep using only the "tested and working" access method. Some > hardware has the A20 stuck to enabled, should not be a problem. Just > display a warning. The memdisk code handles this as well, I believe. My intention was basically to steal it (should be no problem since everything is GPL, right?). > Finally, MEMDISK hooks int 15.87? No, but MEMDISK does invoke 15.87 and needs the A20 gate to be saved and restored. > And I do think that this is a SYSLINUX problem, so CCing them. I'll let HPA respond to this part :-). Anyway, I am willing to do this work. Unless one of the FreeDOS folks wants to step up to the plate? - Pat P.S. Is there any reason NOT to save/restore A20 around INT15/AH=87 ? _______________________________________________ SYSLINUX mailing list Submissions to [EMAIL PROTECTED] Unsubscribe or set options at: http://www.zytor.com/mailman/listinfo/syslinux Please do not send private replies to mailing list traffic. ------------------------------------------------------- This SF.Net email is sponsored by: IBM Linux Tutorials Free Linux tutorial presented by Daniel Robbins, President and CEO of GenToo technologies. Learn everything from fundamentals to system administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click _______________________________________________ Freedos-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/freedos-devel