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grub4dos 0.4.6a with embedded USB 2.0 driver

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#1 ilko


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Posted 07 June 2013 - 10:45 PM

Something very interesting is being cooked:





grub4dos-0.4.6a-2013-05-21- README_GRUB4DOS.txt:




***                           About usb2.0 driver                         ***
When the the bios assigned drive No. 00, and the system does not support extended reading,
Wrong CHS parameter will cause USB drives failed to boot.

As a remedy, loading the usb drive to support extended reading, to re-enable USB booting.

The USB drive code is located in the 11-21 sector of grldr.pbr file.

The USB 2.0 driver supports: PCI Device Class 0c/03/20,
namely EHCI (Enhanced Host Controller Interface) devices.

The USB 2.0 driver supports: USB (Universal Serial Bus) Class 08 (Mass Storage devices),
SubClass 06, Protocol 50, that is USB Thumbdrive or Portable External Hard Drives.

USB driver code should be placed after the PBR sector.

PBR boot program will loads the USB driver first, and then call it.
Resident in the top of conventional memory, USB devices are read and written by intercepting INT 13h.

There is a switch in the PBR offset 0x1fb.
  01: Load driver only if the system does not have extended read/write ability;
  02: Always load driver
  00: USB driver is not loaded.

When USB driver is loaded, it waits for 5 seconds for user input:
  Press s key to load in slow-down mode;
  Press other keys to skip loading driver;
  Otherwise drive will be loaded.
Number of seconds for waiting Offset 0x0a at waiting for the number of seconds by usb driver settings.

Note: Only (FAT12/16/32/ext2/ext3/ext4/exfat) file systems are supported.

Note: USB drives needs to be pre-formatted for getting MBR and BPB parameters.

Tips: 1. Some USB drives are identified as USB 1.x devices under Windows and DOS usbaspi.sys ,
         but they will be identified as USB 2.0 devices when loading in slow-down mode.
      2. Some USB drives do not be detected when plugging into front panel,
         but they will be detected when loading in slow-down mode.



#2 steve6375


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Posted 08 June 2013 - 01:14 AM

hmmm - well this looks like it would solve the USB HDD 137GB limitation that some BIOSes have, however I do not see NTFS in the supported filesystems list and most USB HDDs will be NTFS????

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