A disk copier machine uses a host computer, disk controller, disk drive, and mechanical disk feeder in order to automatically copy information onto each of a number of disks. The selectable format computer disk controller is used in order to connect the host computer to the computer disk drive. The disk controller is constructed to receive format definition program steps from the host computer so that the controller may configure itself to accommodate the particular format of the disk in the computer disk drive. The controller contains standardized process control program steps which are executed inside the controller in order to interact with the particular format definition program provided by the host computer. The process control program is standardized to work with a large variety of disk formats and serves to control the execution of the format definition program, which is a particularized sequence of steps adapted to a particular disk format. The format definition program contains a format definition segment which serves to define the disk format, and an indirect addressing pointer table which is accessed by the process control program in order to control the use of the steps of the format definition segment. The selectable format disk controller is particularly useful for copying computer floppy diskettes so that the same disk copier machine may be used in order to copy disks having any of a variety of format types.