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DOS71BSG

MS-DOS 7.1 FAT32 Bootsector for GPT-partitioned disks

Install / Use

/learn @Baron-von-Riedesel/DOS71BSG
About this skill

Quality Score

0/100

Supported Platforms

Universal

README

  1. About

DOS71BSG is a bootsector for MS-DOS 7.1 FAT32 partitions on a GPT-partitioned disk. Actually, it's 3 sectors, size 1536 bytes.

  1. Create the Binaries

Get JWasm and then run mdos71bs.bat and mresti31.bat. After that step, files dos71bsg.bin and RestI31.SYS should exist. File dos71bsg.bin is the FAT32 boot sector for GPT-partitioned disks and RestI31.SYS is a DOS device driver, used to restore the original Int 13h handler temporarily modified by dos71bsg.bin.

  1. Usage

a) create a FAT32 partition on the disk - must be located entirely in the first 2 TB of the disk! b) use a disk editor (WDe) to save the bootsector to a file. c) copy the BPB of the saved sector ( bytes 0x0B-0x59 ) into file dos71bsg.bin, at the very same location. d) if unsure, use WDe to check if the modified dos71bsg.bin looks correct. e) then write that file to the partition's boot sector ( 3 sectors ). f) ensure that MS-DOS 7.1 IO.SYS is in the partition's root directory. g) use grub-mkconfig to add the partition to grub's boot menu. h) add RestI13.sys to config.sys ( should be the first DEVICE= entry ).

No risk, no fun.

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GitHub Stars21
CategoryDevelopment
Updated2mo ago
Forks1

Languages

Assembly

Security Score

80/100

Audited on Jan 25, 2026

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