See Wikipedia for details.
They were ubiquitous in computer applications from the 1960s to the early 21st century and are still in widespread use in industrial applications. Many data communication standards specify D-sub connectors, e.g V.24/RS-232 (DB-25 connector), X.21 (DA-15 connector), etc.
There are five basic shell sizes, DA through DE (see illustration). Originally, all versions except DD had two rows of contacts. Later, "high density" versions with extra rows were added, the most widely used of which is the familiar DE-15 VGA connector.
Special versions of D-shell connectors exist that replace some groups of contacts with coaxial or high-current inserts. Examples include the video signal connectors on 1990s Sun workstations, and the interface connectors on Tektronix SD-series sampling heads (see photos).
Uses in Tektronix equipment
- DB-25 female in instruments having parallel ("Centronics") printer ports
- DE-9 male (on older instruments, DB-25 male) on many instruments having RS-232 serial interfaces
- DE-15 female on instruments with VGA video output
- DD-50 on DF1 (m) / 7D01 (f)
- DD-50 with four coaxial inserts in 11800 series sampling plugins