Abstract: A base unit for a keyboard is presented. The base unit has a substantially rectangular layout. The base unit includes an equipment portion, formed so that it can be equipped with a plurality of key switches for the keyboard. The equipment portion is arranged on a first side of the base unit. The base unit further comprises at least one coupling portion for mechanically coupling the base unit to an accessory module for the keyboard. Each coupling portion includes a first coupling feature and a second coupling feature. The first coupling feature is arranged on the first side of the base unit, and the second coupling feature is arranged on a second side of the base unit facing away from the first side. Each coupling feature is arranged parallel to a long side of the base unit continuously between narrow sides of the base unit. The first coupling feature is formed for positive locking with a first mounting feature of the accessory module.

Abstract: A portable information terminal includes a body casing which incorporates a function unit for transmitting and receiving information and has a groove portion with a plane bottom, and a card casing which is reversibly and slidably attached in the plane-bottom groove portion of the body casing and has an operation unit. The plane-bottom groove portion of the body casing has a rectangular shape with side surfaces opposed to each other and a pair of guide grooves formed on the opposed surfaces thereof. The card casing has a rectangular shape substantially similar to that of the plane-bottom groove portion and has a pair of pins near the end portions of the opposed side surfaces. The card casing is attached to the body casing by inserting the pair of pins into the pair of guide grooves.

Abstract: A portable information terminal includes a body casing which incorporates a function unit for transmitting and receiving information and has a groove portion with a plane bottom, and a card casing which is reversibly and slidably attached in the plane-bottom groove portion of the body casing and has an operation unit. The plane-bottom groove portion of the body casing has a rectangular shape with side surfaces opposed to each other and a pair of guide grooves are formed on the opposed surfaces thereof. The card casing has a rectangular shape substantially similar to that of the plane-bottom groove portion and has a pair of pins near the end portions of the opposed side surfaces. The card casing is attached to the body casing by inserting the pair of pins into the pair of guide grooves.