Steve, they had a yellow $1 brass-core that was issued before these were, in 1980.
Their first brass-cores used a hyphen between the last "H" and "S" in the word "Harrah's".
These later brass-cores were issued in 1983 if my memory serves me well, and all used a "star" in place of the hyphen. No $1 chips that I am aware of used the "star".