Date: Sun, 22 Jun 1997 17:58:11 -0700 (PDT) From: Tom Samplonius <tom@sdf.com> To: Steve Howe <un_x@anchorage.net> Cc: freebsd-hackers <hackers@freebsd.org> Subject: Re: direct access Message-ID: <Pine.BSF.3.95q.970622175554.22030B-100000@misery.sdf.com> In-Reply-To: <Pine.BSF.3.95q.970622153100.15540A-100000@aak.anchorage.net>
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On Sun, 22 Jun 1997, Steve Howe wrote:
>
> 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?
>
> -------------------------------------------------
> FingerPrint BA09868C 1B995204 58410FD3 A5E7B2DA
> http://www.geocities.com/siliconvalley/way/7747
> -------------------------------------------------
FreeBSD is unix. Unix is a multi-user operating system. Unix uses the
memory management functions of the CPU to protect the memory space of each
process.
I thought everyone knew this?
Tom
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