Usually you can assign up to 14 drive IDs (C:-P:) to partitions on storage devices. The maximum partition size depends on the TOS version. If there are more than 14 partitions, you cannot access them because there are no more drive IDs. With HDDRIVER there are several options to bypass this restriction, e.g. in order to make better use of media with high capacities.
The most obvious solutions are these:
- If you do not need drives A: and/or B:, assign a partition to these IDs with "Devices and Partitions". This will increase the usable partition count from 14 to 16. A: and B: are ideal to map USB floppy drives, e.g. if your regular drive is broken, or if you do not have a second regular floppy drive.
- Use Big-DOS, which supports up to 31 drives (A:-Z: except U: and 1:-6:). Except for the boot partition, which must not be bigger than the maximum partition size supported by the TOS version used, each partititon (FAT16) can have a capacity of up to 2 GiB.
- Use the MagiC operation system, which is a good choice anyway because besides high speed and true multitasking it supports up to 31 drives (A:-Z: except U: and 1:-6:). MagiC supports TOS partitions up to 2 GiB and FAT32 partitions, which can be much bigger than regular TOS partitions. This means that you do not just have more partitions, but these can also be bigger than usual. When partitioning a drive, HDDRUTIL automatically creates a FAT32 partition when the partition size is too big for a TOS FAT16 partition, i.e. bigger than 1 GiB.
- Use MiNT, which supports up to 31 drives (A:-Z: except U: and 1:-6:). Compared to MagiC, MiNT is more complicated to set up and needs more CPU and RAM resources, though. In addition to FAT32 partitions MiNT also supports Linux ext2 partitions, which like FAT32 partitions can be much bigger than FAT16 partitions. Refer to the MiNT documentation on how to set up ext2 partitions.
There is also a less obvious solution, which is less convenient than the approaches above, but works fine in some scenarios: If you do not need access to all partitions at the same time, simply disable the partitions you do not need with HDDRUTIL and "Edit Partitions". This way you can create more partitions than your OS supports, and you only enable those you are interested in. Some partitions might only contain games and others might contain everything else but games, for instance. Depending on what you would like to do with your Atari next you enable/disable the respective partitions and reboot. This approach is quite flexible because you have full control over the combination of available partitions.
You should not disable your boot partition, though ;-).