From: james.harris.1@gmail.com   
      
   On 20/12/2021 04:54, s_dubrovich@yahoo.com wrote:   
   > On Sunday, December 19, 2021 at 4:43:46 PM UTC-6, James Harris wrote:   
      
   ...   
      
   >> So loading would be in at least these parts:   
   >>   
   >> 1. VBR finds OS loader file and loads 1st sector of it.   
   >>   
   >> 2. OS loader's first sector follows the FAT chain to load more of (maybe   
   >> all of) OS loader.   
   >>   
   >> 3. The OS loader is then large enough to do whatever's necessary.   
      
   ...   
      
   > Q.  Is this fat-LFN?   
      
   It doesn't matter. I search for a file by an uppercase 8.3 name so it   
   will work with either. And see below about patents.   
      
   > Q. What is the size of the OS?   
      
   That doesn't come in to it, and is unknown as yet. The boot process has   
   to load something I call the "os loader". Its job will be to load the OS   
   or to offer a boot menu or to produce good diagnostics or whatever.   
      
   > Q. Are you sure the VBR cannot be made to load the entire OS? - eliminating   
   the separate OS Loader?   
      
   Yes, there are lots of checks I want to do before loading the OS proper.   
      
   >   
   > The MBR I use is a vanilla ibm ~32 mb with one volume bootable, with the VBR   
   expected at LBA = 20h.   
      
   I'm using my own MBR for now as it made testing easier but the VBR   
   should work with any normal MBR.   
      
   > The VBR is at LB 20h,  The hobby OS begins at LB 21h and runs for 63.5k, it   
   is outside the file system.  The file system  directory follows the OS, the   
   file data follows the directory area.  The file system is under development,   
   it isn't needed to boot    
   the OS, it will be needed to save data to files and to load utilities. - non   
   fat.   
      
   It's certainly an option to have a custom arrangement and in some ways   
   that's more secure but for now I'm going for the convenience of using   
   standard structures as they are easier to work with.   
      
   Ultimately, I'd like the boot to go via a small dedicated 'boot   
   partition' but that's for the future.   
      
   >   
   > I don't support fat, nor LFN,  LFN is covered by ms patents, so I dropped my   
   work on it.  But back when I was working with fat, that VBR code was enough to   
   load a hobby os off the fat filesystem --non-lfn.   
      
   Aren't patents about production of media? And possibly compiled code?   
   ISTR that source code was not affected.   
      
   >   
   > The VBR that I'm using is of course loaded at 07C00h, it then relocates   
   itself to below the EBDA and continues on to load the OS to 80:0000h, then far   
   jumps to the OS.  The self relocation is simple enough, and gets the vbr boot   
   code out of the way of    
   loading the OS, avoiding the possibility of over-writing itself.   
      
   Sounds good.   
      
      
   --   
   James Harris   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)