In [[IBM mainframe]] [[operating system]]s, '''Execute Channel Program''' ('''EXCP''') is a [[Supervisor Call instruction|supervisor call]] for low-level device access, where the programmer is responsible for providing a ''[[Channel program#Channel Program|channel program]]''—a list of device-specific commands ([[Channel command word#Channel command words|CCW]]s)—to be executed by I/O channels, control units and devices. EXCP is more specifically described in the OS System Programmer's Guide.<ref name="Johnson1989">{{cite manualbook|publisherauthor=IBMRobert H. Johnson|title=IBMMVS: System/360concepts Operating Systemand System Programmer's Guide|id=C28-6550-2|date=March 1967facilities|url=httphttps://wwwbooks.bitsaversgoogle.org/pdfcom/ibm/360/os/R01books?id=HIFQAAAAMAAJ|date=June 1989|publisher=Intertext Publications|isbn=978-08/C280-655007-2_OSsysPrmg_Mar67.pdf032673-6|page=558}}</ref><ref name="Hannula1974">{{cite book|author=Reino Hannula|title=Computers and Programming: A System/360-370 Assembler Language Approach|url=https://books.google.com/books?id=0MgmAAAAMAAJ|year=1974|publisher=Houghton Mifflin|isbn=978-0-395-16796-0|page=431}}</ref> EXCP is more specifically described in the OS System Programmer's Guide.<ref>{{cite manual|publisher=IBM|title=IBM System/360 Operating System System Programmer's Guide|id=C28-6550-2|date=March 1967|url=http://www.bitsavers.org/pdf/ibm/360/os/R01-08/C28-6550-2_OSsysPrmg_Mar67.pdf}}</ref>
