Users that have an UltraSatan or two memory card adapters often use one memory card with a regular TOS compatible partition scheme, and the other with a TOS/Windows compatible scheme, in order to exchange data with a PC or Mac. It can be convenient to assign the partition used for the data exchange to drive B:, in order to save one of the precious drive IDs C:-P:.
In order to achieve this with HDDRIVER, launch HDDRUTIL and enter the "Devices and Partitions" settings. Double-click the ID button for your second memory card. Now enter 'B' as the first drive ID, click on OK, and then again click on OK to save the "Devices and Partitions" settings. After a reboot you should find that B: is now mapped to the first partition of your second memory card.
It is important to note that things get tricky when the second memory card is not scanned as the last device ID, or when there are several partitions on the card. Depending on whether HDDRIVER is configured to preserve existing partition IDs or not there may be unwanted results. Therefore, mapping drives with more than one partition to drive B: is not recommended, and the device ID to be mapped to drive B: should be the last (highest) device ID that is scanned.
You can also assign a partition to drive A:, provided that you do not want to use a regular floppy disk drive. In particular this may be the case if you are using a non-floppy device that supports floppy disks, e.g. an LS-120 or a USB floppy disk drive.