A robotic surgical assembly, comprising: a drive assembly detachably mountable to a surgical robot, the drive assembly including: a chassis; a roll input configured to drivingly couple with a roll output of the surgical robot; a pitch input configured to drivingly couple with a pitch output of the surgical robot; and a clamp/fire input configured to drivingly couple with a clamp/fire output of the surgical robot; and a shaft assembly mounted to the drive assembly; the shaft assembly being elongated along a shaft axis and configured to detachably couple with a stapler reload assembly that includes an end effector operable to clamp and staple tissue, a reload roll shaft to which the end effector is pivotally mounted, a reload pitch shaft translatable along the shaft axis to reorient the end effector relative to the reload roll shaft, and a reload clamp/fire shaft drivingly coupled with the end effector and translatable along the shaft axis to actuate the end effector to clamp and staple tissue; the shaft assembly including: a roll shaft drivingly coupled with the drive assembly so that rotation of the roll input rotates the roll shaft around the shaft axis, the roll shaft having a proximal portion configured to detachably couple to the reload roll shaft; a pitch shaft drivingly coupled with the drive assembly so that rotation of the pitch input translates the pitch shaft along the shaft axis, the pitch shaft having a proximal portion configured to detachably couple to the reload pitch shaft; and a clamp/fire shaft drivingly coupled with the drive assembly so that rotation of the clamp/fire input translates the clamp/fire shaft along the shaft axis, the clamp/fire shaft having a proximal portion configured to detachably couple to the reload clamp/fire shaft, wherein: the roll shaft has a roll shaft lumen extending along the shaft axis; the pitch shaft is accommodated within the roll shaft lumen; the pitch shaft has a pitch shaft lumen extending along the shaft axis; and the clamp/fire shaft is accommodated within the pitch shaft lumen, characterized in that the pitch shaft is constrained to rotate with the roll shaft around the shaft axis, and the clamp/fire shaft is constrained to rotate with the roll shaft around the shaft axis. a drive assembly detachably mountable to a surgical robot, the drive assembly including: a chassis; a roll input configured to drivingly couple with a roll output of the surgical robot; a pitch input configured to drivingly couple with a pitch output of the surgical robot; and a clamp/fire input configured to drivingly couple with a clamp/fire output of the surgical robot; and a chassis; a roll input configured to drivingly couple with a roll output of the surgical robot; a pitch input configured to drivingly couple with a pitch output of the surgical robot; and a clamp/fire input configured to drivingly couple with a clamp/fire output of the surgical robot; and a shaft assembly mounted to the drive assembly; the shaft assembly being elongated along a shaft axis and configured to detachably couple with a stapler reload assembly that includes an end effector operable to clamp and staple tissue, a reload roll shaft to which the end effector is pivotally mounted, a reload pitch shaft translatable along the shaft axis to reorient the end effector relative to the reload roll shaft, and a reload clamp/fire shaft drivingly coupled with the end effector and translatable along the shaft axis to actuate the end effector to clamp and staple tissue; the shaft assembly including: a roll shaft drivingly coupled with the drive assembly so that rotation of the roll input rotates the roll shaft around the shaft axis, the roll shaft having a proximal portion configured to detachably couple to the reload roll shaft; a pitch shaft drivingly coupled with the drive assembly so that rotation of the pitch input translates the pitch shaft along the shaft axis, the pitch shaft having a proximal portion configured to detachably couple to the reload pitch shaft; and a clamp/fire shaft drivingly coupled with the drive assembly so that rotation of the clamp/fire input translates the clamp/fire shaft along the shaft axis, the clamp/fire shaft having a proximal portion configured to detachably couple to the reload clamp/fire shaft, wherein: a roll shaft drivingly coupled with the drive assembly so that rotation of the roll input rotates the roll shaft around the shaft axis, the roll shaft having a proximal portion configured to detachably couple to the reload roll shaft; a pitch shaft drivingly coupled with the drive assembly so that rotation of the pitch input translates the pitch shaft along the shaft axis, the pitch shaft having a proximal portion configured to detachably couple to the reload pitch shaft; and a clamp/fire shaft drivingly coupled with the drive assembly so that rotation of the clamp/fire input translates the clamp/fire shaft along the shaft axis, the clamp/fire shaft having a proximal portion configured to detachably couple to the reload clamp/fire shaft, wherein: the roll shaft has a roll shaft lumen extending along the shaft axis; the pitch shaft is accommodated within the roll shaft lumen; the pitch shaft has a pitch shaft lumen extending along the shaft axis; and the clamp/fire shaft is accommodated within the pitch shaft lumen, characterized in that the pitch shaft is constrained to rotate with the roll shaft around the shaft axis, and the clamp/fire shaft is constrained to rotate with the roll shaft around the shaft axis.