In order to utilize a resource in MUMPS, first gain access to the resource (ex: make OS call to set up printer), then use the resource, then release the resource for further use by others.
Device types: (not exhaustive, GT.M implementation)
|TRM||Terminal or Printer|
|SD||Sequencial disk file|
MUMPS uses device numbers to access resources and to interface with devices when using the OPEN, USE or CLOSE commands. Implementations vary and device types are not standardized across implementations.
Example of possible device numbers: (UCD MicroMUMPS implementation, example out of date)
|5||External Communications port|
Device numbers can be used to access the resource after it has been opened.