A robotic surgery apparatus comprising: a surgical instrument for use at an internal operative site of a subject; a mechanically drivable mounting unit on which the surgical instrument is mounted, the mounting unit being drivably movable outside the operative site of the subject; an electrically driven drive unit for driving movement of the mounting unit; mechanical cabling drivably intercoupled to the mounting unit at one end of the cabling; the mechanical cabling having another end which is readily drivably couplable to and decouplable from the drive unit. The drive unit being readily manually portable and readily attachable to and detachable from a fixed support on or relative to which the subject is mounted.