FAT [Retro-PC series]

Gil Megidish via Flickr

To get an authentic MS-DOS to my Retro-PC, I needed to think of the filesystem first. MS-DOS file system, FAT, evolved over time, and the latest version on (a standalone) MS-DOS was FAT16. If you want to utilize more than 2 GB disk space with MS-DOS 6.22, Windows 95 or even with the earlier versions of Windows 98, you need to create multiple partitions with drive letters C, D, E, and so on.

Multiple FAT partitions need to be set up in a certain way. On MBR, a boot (PRI) partition is required for booting the operating system and is always revealed as drive “C” in MS-DOS. Additional drives have to be installed on extended (EXT) partition containing multiple logical partitions (drive letter “D”, “E” and so on). This scheme takes, at least, two out of four primary partitions (PRI or EXT) you are allowed to have with MBR, and this can later be problematic as you may want to install more operating systems. If you have multiple physical hard drives, you could have a strategy to use the first one for MS-DOS and Windows 98, and the second one for Windows XP and Ubuntu, and still have enough primary partitions. I did not have this luxury, as the small factor desktop of mine only takes in one 3.5” hard drive.

MS-DOS games do not consume much disk space, and you may ask yourself, do I need more than 2 GB (= roughly 1400 HD diskettes or 3 full CD-ROMs)? If the answer is yes, you probably want FAT32, and you definitely can create a single partition big enough to fit in all the DOS software you ever owned. To install a real DOS with FAT32, your options are limited to MS-DOS 7.1 (unofficial release), FreeDOS or Windows 98SE/ME in MS-DOS mode. I will choose one of those to my Retro-PC in the next post.