The upd part of the command might indicate that the tool is updating the memory dump with new data or modifying the existing dump in some way.
The Sahara protocol uses a specific set of commands and responses to interact with the device. When executing a memory dump, the host computer sends a request to the device, which responds with a block of memory data. The QPST software tool likely provides a convenient interface for sending these requests and processing the responses.
A very specific and technical topic!