part.htm

一个Win95/98/NT下的分区管理程序

   When you install it you have 4 options: 
   
       - Enable check for <A HREF="#virus">boot viruses</A>
       - Prompt's time-out
       - Default partition (overrides remembered "last selected")
       - Default place to boot from if none of the partitions are active.
         The choices are A: and the next hard drive.

   Hint: if you set default partition to A then computer will always
         boot from A:, if to Tab - from the next hard disk, and when
         set to Space - then it will stop and wait for your choice.

<HR>

<A NAME="ipl_mesg"></A>Understanding messages of Compact Boot Manager

       Message                         Description

                          Press ESC to skip prompt and boot OS
                          Press SPACE to stop and wait for selection
"Booting from: HD1/1..."  Press 1-4 to boot from corresponding partition
"Booting from: HD1/_"     Press A to boot from a floppy or TAB to boot 
                          from the next hard drive. Any other key will
                          resume booting, and will remain in the buffer.
                          For instance F4, F5, F8, ... (see <A HREF="#hints">hints</A>)

"Writing changes..."      IPL is saving your selection into MBR.

"Error!"                  Error reading disk or empty partition selected.

"Virus !!!"               IPL found that one of interrupt vectors doesn't
                          point to ROM BIOS memory (see <A HREF="#virus">virus protection</A>).
                          You can press ENTER to resume booting, but it
                          would be better to shut down the computer and
                          run antivirus program, after booting from a
                          clean floppy disk.

<HR>

<A NAME="virus"></A>Virus protection

      IPL that comes with this program can detect viruses even before
   operating system gets into memory. This is important, because some
   <A HREF="#mbr">MBR</A> viruses cannot be detected by antivirus programs that are
   loaded after operating system.

      Virus detection is implemented by checking 29 interrupt vectors
   from int 0h to int 1Ch. They must point to addresses C000:0000h or 
   higher, where ROM BIOS resides. These interrupts control all vital
   functions of the system, such as Timer, Video, Keyboard, and Disk.
   
      If any of the interrupts have been changed it is very likely that a
   virus invaded the system. In this case the IPL stops and warns user.
   You have a choice to continue booting with virus in memory or rebooting
   the system and run antivirus. See <A HREF="#ipl_mesg">IPL messages</A> section.

      However, on some systems this method of checking for virusus will
   produce false alarms. In this case you can disable virus detection.
<A NAME="hints"></A>
       Another way of protection from viruses is to avoid accidental boots
   from the floppy drive. With this program you can do that, while still
   being able to boot from floppy, when you need it.  To do that:

     1. Install either Advanced or Compact Boot Manager that comes with
        this program.

     2. Change boot sequence to C:,A: in the BIOS setup 
    
     3. When you need to boot from A: at the <A HREF="#ipl_mesg">boot time</A> press A.

     This trick will not only save you from viruses, but will also speed
  up your work. It is especially impressive if you have QEMM 8.xx together
  with MS-DOS or Windows 95. 

     Set "BootFloppy:N" option in QEMM's quick boot and add "SWITCHES=/F"
  to your CONFIG.SYS file.

     Next time, when you reboot QEMM's Quick Boot will skip BIOS memory
  test and take you straight to the Compact Boot Manager's prompt where
  you will be more comfortable with pressing F4, F5, or F8 ...

<HR>

<A NAME="create"></A>Creating a new partition

      To create a new partition find unused record in the partition
   table and press INS, then select desired File System type.
   
      After you do that Partition Manager will automatically put values
   for cylinders, heads, and sectors. 
   
      In most cases you don't need to modify those values. But if you 
   have in mind your own partitioning scheme you can change them. When
   you do that, do start and end partitions on the cylinder (or head)
   boundaries. It is not required, but highly recommended. For example,
   if your hard  disk has 16 heads and 63 sectors per head, you should
   start partition on head 0, sector 1 and end on head 15, sector 63.
   
<A NAME="0xFF00"></A>
      If you need to install several operating systems such as MS-DOS,
   Windows 95, or Windows NT, and you want to avoid their interference
   with each other you may want to hide existing partitions, while
   installing operating system into a new one, and unhide them later. 

      While you are entering numbers partition may turn red. Don't
   worry about it until you finish.
<A NAME="conflict"></A>
      The red color of the partition means that the settings appear
   to be invalid or conflicting with the current disk geometry.
   
      To help you figure out what's wrong I had defined four error codes.
   They are shown in red color on the right when you move cursor on the
   invalid partition.
      
   mbr: partition overlaps MBR in the first sector of the disk or
        extended dos partition.
        
   range: partition have values for cylinder, head, or sector (CHS)
        outside of the range of disk or extended dos partition boundaries
        or it ends before it begins. Move cursor on the CHS fields to see
        the hint with allowed values.

   overlapped: two partition are overlapping each other.
   
   inconsistent: this message means that CHS values do not correspond
        to starting sector and partition size, which are also stored
        in the partition table. Usually this happens if partition table
        was damaged or BIOS disk geometry translation has changed since
        partition table was last modified. This error will also appear
        if you have value 0 for sector (sector must be at least 1).
        
      If the red color appears as soon as you started it may be because
   you have changed disk controller or BIOS settings or MBR was corrupted.
   If this is the case don't change any values unless you are absolutly
   sure what you are doing.
      Hint for the professionals: no matter how BIOS represents disk 
   geometry the relative number of sectors and partition sizes hold. 
   To fix the problem of inconsistency you have to switch to the LBA mode
   by pressing F4, note the size of the partition, change it and then
   change it back to the correct size. This will force the program to
   recalculate the values in CHS according to the current disk geometry.
      However, keep in mind two things: As far as I can tell DOS uses
   CHS values to boot and doesn't use starting sector/number of sectors
   fields. Instead, it uses field "sectors prior partition" and
   "big total number of sectors" from its boot record.

      If you had used OnTrack DDO or Ez-Drive you should know that they
   skew disk: OnTrack by 63 sectors and Ez-Drive by 1 sector. Therefore
   you have to reflect this change in DOS boot records.

<HR>

<A NAME="format"></A>Formatting partition
      
      You can format partitions or just check disk surface for bad sectors
   without destroying the data. 
   
      To verify any partition press V in interactive mode or run:
      
             part -v n

      To format partition press F in interactive mode or run:
      
             part -f n options ...
      
      Format options depend on <A HREF="#systems">file system</A> that you are formatting.
   
Important notes on formatting DOS partitions

      First of all DOS cannot see newly created partition, untill you
   reboot computer, because it scans partition table only once.
      So if you created and/or formatted a new partition you have to
   reboot before you can use it.
   
      If the partition already mounted (you can see it as a DOS drive)
   and you formatted partition with different parameters you also have
   to reboot computer, because DOS keeps in memory old numbers, and will
   most certainly mess up the disk if you will try to write to it
   without rebooting.

      The other problem is disk caches. Partition Manager flushes them
   using SmartDrive v 4.00+ API. Most of the new cache programs, such as
   PC-Cache 8.0, NCACHE2, SpeedDrive support it. But if you have any
   other cache you should disable it before formatting DOS partitions
   or reboot computer after formatting.

      The difference in behaviour of part.exe and format.com is that
   part formats partitions by number in partition table and format by
   letter in DOS device list. Therefore before rebooting you shouldn't
   use programs that accesses partitions via DOS, but you can use 
   programs that writes to partitions bypassing DOS. For example zpart,
   which compresses and decompresses entire partitions to and from files.

      Limitation: currently this program cannot format logical DOS drives
   from the command line - you have to go to the interactive mode.

<HR>

<A NAME="os_inst"></A>Important issues on installation of a new OS

      Windows 95 and some other operating systems upon installation
   replace your current <A HREF="#ipl">IPL</A> with their own code. If you have 
   Compact or Advanced boot managers installed on your hard drive you
   would not see them at the next boot.

      I have worked on this issue. It should not lead to the loss of
   data, at least with Windows 95. In the worst case you just would have
   to run part.exe and reinstall boot manager. But to ensure that nothing
   will be lost do the following steps before installing new OS:
   
      - Create a bootable floppy and copy Partition Manager on it.
      - Run Partition Manager and create partition for the new OS.
      - If possible format it using Partition Manager.
      - In Advanced Boot Manager edit boot menu (see <A HREF="#setup_adv_example2">example</A>)
      - Save Partition Manager's data to the floppy.
      - Reboot computer and install a new OS
   
      If MBR will be modified by OS installer review the changes and
   reinstall boot manager. (Press F2 in order to save MBR and install 
   Advanced Boot Manager executable code to disk).
   
<HR>

<A NAME="systems"></A>Supported file systems

      <A HREF="#0x0000">Unused partition</A>
      <A HREF="#0x0100">Classical MS-DOS file systems</A>
      <A HREF="#0x0B00">Windows 95 FAT-32 file system</A>
      <A HREF="#0x0500">Extended DOS partition</A>
      <A HREF="#make_primary">Making logical drives bootable</A>

<HR>
<A NAME="0x0000"></A>Unused partition

      This simply indicates that entry in partition table is available.
   It doesn't tell anything about free space on disk. You have to figure
   out that yourself.

      However if you specify starting and ending locations of partition
   with type "Unused" Partition Manager will let you format and verify
   the disk space.
   
      Format takes two options: "/destructive" or "/clean". First one
   performes low level disk format, second one fills disk space with
   zeros.

<HR>
<A NAME="setup_fat"></A><A NAME="0x0100"></A><A NAME="0x0400"></A><A NAME="0x0600"><A NAME="0x1100"></A><A NAME="0x1400"></A><A NAME="0x1600"></A>Classical MS-DOS file systems

	0x01, "DOS FAT-12"
	0x04, "DOS FAT-16 (under 32M)"
	0x06, "BIGDOS FAT-16 (over 32M)"

   All file systems have the same structure:
      
   	[Boot Sector]
   	[First copy of FAT]
   	[Second copy of FAT]
   	[Root Directory]
   	[Cluster 2]
   	[Cluster 3]
   	[Cluster 4]
   	...

      Boot sector, FATs, Root Directory, and clusters have fixed sizes,
   which you  can set only when you are formatting the disk.
      Space for all subdirectories and files is allocated by clusters.
   If cluster size is 8 sectors = 4,096 bytes, when you create file with
   size of 1 byte it will get entire 4,096 bytes cluster.
      There is an entry in FAT (File Allocation Table) for each cluster,
   which tells if cluster is free, allocated, or damaged. Therefore size
   of the FAT determines maximum number of clusters.

      FAT-12 file system is limited to 4084 clusters. It is used on the 
  floppy disks, but you can also use it on a small hard disk partition.