computer in which an optional unit is installable

The present invention relates to a computer to which an optional unit may be attached. The optional unit may be a wireless LAN unit including a wireless LAN adapter and the like. The present invention is directed to a computer in which an optional unit such as a unit including a wireless LAN adapter is installable. The computer including at least a computer body, a display, and a keyboard. The invention is also directed to a note book computer , which includes a computer body with a keyboard, and a display workable as a lid being opened and closed free with the computer body. In these computers with an optional unit , the optional unit is detachably attached to the top of the display, or the optional unit is detachably attached to a portion of the display, the portion being at a side of the display when the lid is closed and being at a top of the display when the lid is opened.