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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
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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