Patent ID: 7068577

Claim:
A disk drive comprising: a tray on which a disk is mounted, a pickup adapted to read information stored in the disk mounted on said tray, a pickup controller adapted to control an information reading mode of said pickup, and a disk type determination element adapted to determine whether the disk mounted on said tray is a write-once type disk, wherein said pickup controller includes: a counter adapted to store therein a first number representing the number of disks, in which information is written in program memory areas thereof, among write-once type disks which are mounted on said tray, and a second number representing the number of disks, in which information is not written in program memory areas thereof, among the same write-once type disks, said pickup controller being adapted to have the pickup start reading information from the program memory areas of the disks during a disk spin-up operation when the first number is larger than the second number, and have the pickup start reading information from lead-in areas of the disks during the spin-up operation when the second number is larger than the first number, said counter having an upper limit to storable first or second numbers, said counter being adapted to compute a difference between the first and second numbers when either one of the first number and second number reaches the upper limit, reset the first and second numbers, and store the difference as one of the two numbers.