The Maintenance Operation Protocol (MOP) is used for utility services such as uploading and downloading system software, remote testing and problem diagnosis. It was a proprietary protocol of Digital Equipment Corporation.MOP frames can be one of the following commands:[1]
| Command | Description | |
|---|---|---|
| [memory load data] | Contains memory load data. | |
| [mem load request] | Request for memory load segment. | |
| [mem load w/addr] | Memory load with transfer address. | |
| [par load w/addr] | Parameter load with transfer address. | |
| [dump service req] | Request for assistance with dump operation. | |
| [mem dump request] | Request for next memory dump segment. | |
| [memory dump data] | Contains memory dump data. | |
| [dump completed] | Acknowledgment of dump completion. | |
| [volunteer assist] | Offer of dump/load/loop assistance. | |
| [request program] | Request for system or loader program. | |
| [rem boot request] | Request for boot program. | |
| [remote ID reqst] | Request for remote console identification. | |
| [remote system ID] | Remote console identification information. | |
| [counters request] | Request for communication information counters. | |
| [counters reply] | Communication information counters. | |
| [reserve console] | Remote console in reserved state. | |
| [release console] | Release of remote console from reserved state. | |
| [rem console poll] | Poll of remote console for status. | |
| [rem console rply] | Response to remote console poll. | |
| [loopback request] | Request to loopback enclosed data. | |
| [loopback reply] | Response to loopback request with data. |