Note: this chapter is in
outline format and will be fleshed out later
ST-506
Colloquial designation for all early drives based on the Shugart ST-506
drive.
An early 111 MB
ST-506-type drive next to a modern 2.5-inch 6.4 GB IDE hard drive.
Had separate control and data cables.
A later (physically
smaller) ST-506-type drive with controller and cables. Notice the second
drive connector on the data cable. The second control cable connector is
visible below the in-use connector on the controller card.
Early ST-506 drives used an encoding method called modified frequency
modulation (MFM). Later drives used an encoding method called run-length limited
(RLL). The details and differences won't be discussed here except that RLL
drives packed 1.5 times as much data into the same space as MFM drives. The
first RLL drives were the same ones manufactured as MFM drives but held 50% more
data.
A typical ST-506 controller had a single data cable connected to both drives
and control cables. Most controllers also had a floppy disk drive controller.
ST-506-type drives are completely obsolete, usually found in museums and
electronic surplus stores.
ESDI
A newer type of ST-506 drive. They are completely obsolete but still
functional as doorstops.
