Does anyone know what File System the DOS 6.22 used/uses (this is important)?

MSDOS (Microsoft Software Disk Operating System) Version 6.22 was for windows 1 to windows 3.1 and windows for work groups used FAT16 (File Allocation Table 16 bits), In the 70's every computer manufactures used their own DOS system Tandy Computers used TRS (Tandy Radio Shake) there was IBM Dos, Amega Dos, DR Dos these were the days before windows came out, Windows 98, ME used FAT32