A family of Pentium-compatible CPU chips from AMD introduced in 2001. Departing from the traditional MHz designation, Athlon XP chips use model numbers that combine clock speed and architectural features into a numerical rating. For example, the 1500+, the first XP model, had a clock speed of 1.33 GHz, but provided greater performance than the earlier Athlon 1.4 GHz chip. See Athlon.