But you will need a Master Boot Record so use the Windows command bootsect /nt6 x: /force /mbr and it will overwrite the NT6 bootsector with a duplicate while also adding the optional MBR which is essential for booting, where x: is the actual volume of your USB device as seen by Windows. But for booting Linux you won't need BOOTMGR or a BOOT folder when using Syslinux. This would give you a Windows NT6 boot sector at the beginning of your FAT32 volume which will not boot to DOS but will instead seek a BOOTMGR file and an accompanying BOOT folder containing some NT6 bcd-style boot files. The modern alternative in Windows10/11/Linux would be to partition the zeroed USB, and set it active, followed by formatting it FAT32 using Windows. A DOS boot sector would then seek DOS bootfiles on that FAT volume and if present you get a DOS command prompt. Then ejecting the floppy and rebooting to the USB instead, the motherboard would then detect the USB as a regular drive with its recognizable geometry, read the Master Boot Record at sector 0 then jump to the Volume Boot Sector of the (primary) partition marked as active at the time. Also before the USB would boot you would need an OS or at least some boot files to be present on the FAT32 volume, which was accomplished when booted to DOS by running SYS.COM on the target device which would write the 3 DOS OS files to the FAT USB. FDISK /MBR is best run when booted to DOS from a floppy (or some optical media), while the USB device is already plugged into the PC and there are no other drives connected to the motherboard, because FDISK /MBR will silently write the standard DOS MBR to sector 0 of the C: drive. For booting you would still further need an actual Master Boot Record to be written to sector zero (to accompany the partition table already there) which would require careful use of the undocumented DOS FDISK switch /MBR. Once formatted the volume would then physically start with a DOS Bootsector in place at its detected location, often sector 63 but also sector 16, 32, 64, 1024, or other choices can also be where the "native" volume might start instead. Lots of people have never done this since DOS is so out-of-date, plus DOS did not support USB anyway so you had to plug in the USB device before you boot the PC so the BIOS can recognize the USB as a drive to begin with before DOS can then format it. This can make all the difference when it comes to bootability. Once partitioned in response to low-level detected geometry, the USB device would then be formatted as FAT32 in DOS/Win9x, once again allowing the traditional OS to detect its preferred geometric layout, this time within the provided partition. The partition must also be "marked active" before it will be a bootable one, which is an important option to select when partitioning. The USB device can then be partitioned MBR-style based on what the BIOS/OS detects regarding the native geometry of the device, without having a potentially nonideal sector 0 or other misleading data previously on the USB remain existent, which the partitioning and/or formatting process would prefer to replicate. Traditionally a target USB device would be zeroed before inserting into the socket of a DOS/Windows/Linux PC. The intention was to get a Linux ISO to boot from a HDD, you copy all files and folders from the optical disk (or mounted ISO) to the FAT volume of the HDD, rename its ISOLINUX folder to SYSLINUX, rename the contained isolinux.cfg file to syslinux.cfg, then "syslinux" the FAT volume and it will write a Syslinux boot sector to the volume which will then load and run the live fileset from FAT not much differently than if it was on an optical disk. The other parts of the Syslinux Project are Extlinux for network booting, and of course Syslinux proper for booting from FAT partitions. Which means the ISO when burned to an optical disk or mounted will have an ISOLINUX folder in the root of its filesystem, and within that folder will be the boot files which allow it to boot as an optical disk. The master image is simply written bitwise to the target regardless of differences in the "heads & sectors" that might be native to the target USB device, which can be a show-stopper when it comes to bootability, or it can compromise erase-block alignment which can dramatically slow the performance of an otherwise good master file set.īootable ISO's are made to boot using the Isolinux proper approach, one part of the overall Syslinux Project. Things like Etcher or dd are nonideal when the "drive geometry" of the master that was imaged is not fully compatible with the target USB device and/or its bootability. Ignorance is not complete failure, just minor lack of awaremess sometimes.
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