Once you have decided to buy an MO drive, which type should you choose? This section contains some things which you need to consider.

What disk capacity do you need? Of course this depends on what you will be using the drive for. For storing a large quantity of files downloaded from the Internet, or backing up a large collection of floppy disks, using higher capacity disks can be much more convenient.

For professional use, a 2.6GB or 5.2GB 5¼" drive is a possibility. These drives are widely used in professional audio and video applications, e.g. for direct-to-disk audio recording. For most users, the cost of 5¼" drives will be too high, though used older-generation drives are sometimes available very cheaply.

This narrows it down to a 3½" unit, either 640MB or 230MB. I think the higher cost of a 640MB drive is well worth it, given the extra storage capacity and data transfer speed.

Which manufacturer's product should you buy? The Fujitsu DynaMO 640SE or Philips MO 640 may be the best value 640MB external drives. The Fujitsu model comes in a dark-coloured casing, while Philips' rebadged version has a white/cream colour casing. Fujitsu also make a faster 3½" mechanism with a spin speed of 4300rpm, compared to 3600rpm for their other drives. You may want to investigate which companies sell units incorporating this faster mechanism; I believe the DynaMO 640SE uses the slower 3600rpm drive.

Recently Fujitsu introduced a new line of 640MB drive mechanisms, which have an improved seek time, 28ms average compared with 35ms for the older M2513 drives. The new MCC3064 mechanism is used in the DynaMO 640SE, but some drives from other companies may still use the older M2513 mechanism. Getting a drive with the faster seek time is a good idea, especially if you are planning on using it for intensive applications, e.g. use like a hard drive for booting from.

Olympus recently introduced their own external 640MB drive. I do not know what this costs, but it may be a good option.

The best 230MB drive mechanism is made by Olympus. External units are sold by Olympus and Philips; they are identical apart from the case colour. This drive has a 4500rpm spin speed and 1MB cache.