Legacy-free PC Legacy-free PC A legacy-free PC is a type of personal computer that lacks a floppy drive, legacy ports, and an Industry Standard Architecture (ISA) bus (or sometimes, any internal expansion bus at all). According to Microsoft, "The basic goal for these requirements is that the operating system, devices, and end users cannot detect the presence of the following: ISA slots or devices; legacy floppy disk controller (FDC); and PS/2, serial, parallel, and game ports." The legacy ports are usually replaced with Universal Serial Bus (USB) ports. A USB adapter may be used if an older device must be connected to
Parallel manipulator others, rather than being cumulative. Each actuator must still move within its own degree of freedom, as for a serial robot; however in the parallel robot the off-axis flexibility of a joint is also constrained by the effect of the other chains. It is this closed-loop stiffness that makes the overall parallel manipulator stiff relative to its components, unlike the serial chain that becomes progressively less rigid with more components. This mutual stiffening also permits simple construction: Stewart platform hexapods chains use prismatic joint linear actuators between any-axis universal ball joints. The ball joints are passive: simply free to move,