Slates, which resemble writing slates, are Tablet PC's without the dedicated keyboard. Keyboards are usually attached via a wireless or USB connection.
These Table PC's incorporate small LCD screens typically 8.4" x 14.1" ( 21-36cm) and have been popular for some time in the vertical markets eg health care, education and field work.
Slates are often designed with mobility in mind - less weight and bulk to carry.
Rugged Tablet PC's models are usually in the Slate form genre, as there are less moving parts to damage.
