Abstract: A logic cell structure includes a first portion, a second portion and a third portion. The first portion, arranged to be a first layout of a first semiconductor element, is placed in a first cell row of a substrate area extending in a first direction. The second portion, arranged to be a second layout of a second semiconductor element, is placed in a second cell row of the substrate area. The third portion is arranged to be a third layout of an interconnecting path used for coupling the first semiconductor element and the second semiconductor element. The first, second and third portions are bounded by a bounding box with a height in a second direction and a width in the first direction. Respective centers of the first portion and the second portion are arranged in a third direction different from each of the first direction and the second direction.

Abstract: A roller board includes a base plate with a cam retaining bore and an accommodating chamber. A roller unit includes a caster mounted rotatably to the base plate underneath the retaining bore, and a roller journalled to the caster. A cam, in the form of a rotatable shaft, is connected to the caster, extends into the chamber via the retaining bore in the base plate, and has a top end which defines an annular cam face with a pair of diametrically opposite lowermost points and a pair of diametrically opposite uppermost points between the lowermost points. A cam follower is disposed within the chamber, and includes an urging spring that has a first end fixed to the base plate and a second end disposed above and abutting against the cam face for urging the cam in an axial direction relative to the cam.