China DOS Union

I want to find a DOS system that is smaller than the current DOS 7.1 modified by moderator Wengier (IO.SYS, MSDOS.SYS, COMMAND.COM total 215K), and that both supports FAT32 partitions and can return error codes (that is, the code returned after COMMAND /Z), preferably around 150K in size. (PC-DOS 7.1 etc. are small enough, but unfortunately can't return error codes.)
Thanks!

At present it seems there is no DOS system more powerful, more practical, and with better compatibility than MS-DOS 7.1, so just use it.

Because I made a boot disk and need to use error codes, but because there's not enough space on the floppy disk, what should I do?

MS-DOS 7.1 is already the DOS with the best compatibility, and it's the most suitable to put on a boot disk (actually, considering its functions and compatibility, its size is not large), while the other DOS systems all have various other bugs or compatibility problems. For example, PC-DOS 7.1 has very poor support for certain hard disks and programs, etc.