What about simply changing to the root folder? c: asm\dosbox\snasm68k.exe /j src\ /p /k %flags% src\source.asm,bin\emu\rom.bin,bin\emu\rom,bin\emu\rom > logs\emu.log ...assuming that the folders are also accessible as c:\asm, c:\bin, etc. (not c:\foo\asm, c:\bin\foo, etc.) Nope @echo off rem save …

Contrary to your criticism, inserting environment variables in commands does not work from the prompt in real DOS; it only works in batch files. So in terms of compatibility with DOS, official DOSBox gets it right and Daum does not. That's a bit surprising and I don't have real DOS to confirm, but …

@echo off rem save the old path @echo on SET oldpath=%path% @echo off rem set the path to the working folder, otherwise compilation will fail @echo on path c:\;%path% @echo off rem delete old assembled binary if it exists @echo on if exist ..\..\bin\emu\rom.bin del ..\..\bin\emu\rom.bin @echo off …

You have commas in the "/o op+,os+,ow+,oz+,oaq+,osq+,omq+" portion. Could those be interfering with the parsing, since snasm68k.exe uses commas to separate the paths that follow? If so, perhaps doing... set var1=/o op+,os+,ow+,oz+,oaq+,osq+,omq+ ..\..\asm\dosbox\snasm68k.exe /j ..\..\src\ /p /k % …

I am using the following batch file to assemble my game: @echo off rem save the old path @echo on SET oldpath=%path% @echo off rem set the path to the working folder, otherwise compilation will fail @echo on path c:\;%path% @echo off rem delete old assembled binary if it exists @echo on if exist …