I thought I’d slap together some github thing with MS-DOS 2.11 that’s been made buildable thanks to a whole host of other smart people. The default stuff out there expects you to build it under MS-DOS using the long obsoleted ‘append’ utility which can add directories to a search path. Instead I created a bunch of makefiles that take advantage of MS-DOS Player, and let you build from Windows.

dos211: just the MS-DOS 2.11 sources, I re-aranged stuff and made it (slightly) easier to rebuild on Windows. (github.com)

building should be somewhat straightforward, assuming you have the ms-dos player in your path. JUST MAKE SURE YOU UNZIP as TEXT mode. If you are getting a million errors you probably have them in github’s favourite unix mode.

D:\temp\dos211-main\bios>..\tools\make
msdos ..\tools\masm ibmbio.asm ibmbio.obj NUL NUL
The Microsoft MACRO Assembler , Version 1.25
 Copyright (C) Microsoft Corp 1981,82,83


Warning Severe
Errors  Errors
0       0
msdos ..\tools\masm sysimes.asm sysimes.obj NUL NUL
The Microsoft MACRO Assembler , Version 1.25
 Copyright (C) Microsoft Corp 1981,82,83


Warning Severe
Errors  Errors
0       0
msdos ..\tools\masm sysinit.asm sysinit.obj NUL NUL
The Microsoft MACRO Assembler , Version 1.25
 Copyright (C) Microsoft Corp 1981,82,83

DOSSYM in Pass 2

Warning Severe
Errors  Errors
0       0
msdos ..\tools\LINK IBMBIO+SYSINIT+SYSIMES;

   Microsoft Object Linker V2.00
(C) Copyright 1982 by Microsoft Inc.

Warning: No STACK segment

There was 1 error detected.
msdos ..\tools\exe2bin.exe IBMBIO IBMBIO.COM < 70.TXT
Fix-ups needed - base segment (hex): 70
del -f ibmbio.obj    sysimes.obj   sysinit.obj ibmbio.exe

D:\temp\dos211-main\bios>

As an example building the bios by running make. For the impatiend you can download dos211.zip, which includes a bootable 360kb disk image, and a 32Mb vmdk!