Date: Sun, 22 Jun 1997 15:43:36 -0800 (AKDT) From: Steve Howe <un_x@anchorage.net> To: freebsd-hackers <hackers@freebsd.org> Subject: direct access Message-ID: <Pine.BSF.3.95q.970622153100.15540A-100000@aak.anchorage.net>
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i wanted to port a hex/block editor from DOS.
it can read/write 1 RAM blocks
2 Port Addresses
3 Hard/Floppy Drives
4 Files
however, i am finding even simple things like ...
/////////////////////////////////////////////////
int main (void) {
unsigned char * p = (unsigned char *)0x000b8000;
while ( 1 ) { printf("%c", *p++); getch(); } return 0;
}
/////////////////////////////////////////////////
where i try to read the CGA/VGA screen, bomb with
"segmentation violation" errors.
is the kernel examining op codes on the run, or what?
is it at all possible to write Device editors?
at any level of coding?
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FingerPrint BA09868C 1B995204 58410FD3 A5E7B2DA
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