GDDM (Graphical Data Display Manager) is a computer graphics system for the IBM System/370 which was developed in IBM's Hursley lab, and first released in 1979. GDDM was originally designed to provide programming support for the IBM 3279 colour display terminal and the associated 3287 colour printer. The 3279 was a colour graphics terminal designed to be used in a general business environment.

GDDM was extended in the early 1980s to provide graphics support for all of IBM's display terminals and printers, and ran on all of IBM's mainframe operating systems.

GDDM also provided support for the (then current) international standards for interactive computer graphics: GKS and PHIGS. Both GKS and PHIGS were designed around the requirements of CAD systems.

GDDM is also available on the IBM i midrange operating system, as well as its predecessor, the AS/400.

GDDM comprises a number of components:

• Graphics primitives - lines, circles, boxes etc.
• Graphing - through the Presentation Graphics Feature (PGF)
• Language support - PL/I, REXX, COBOL etc.
• Conversion capabilities - for example to GIF format.
• Interactive Chart Utility (ICU).

GDDM remains in widespread use today, embedded in many z/OS applications, as well as in system programs.