Compatible data storage apparatus for use with disk assemblies of two or more different storage capacities

Claim 1

In a disk storage apparatus having a transducer for writing and reading data on first, second and third replaceable disk assemblies of different storage capacities at first, second and third data transfer rates, respectively, each disk assembly having a disk enclosed in a housing, the first and second disk assemblies having a first and second capacity discriminate window, respectively, formed in different prescribed positions in the housings thereof by way of contradistinction from each other and from the third disk assembly, which has no such capacity discriminate window, the improvement comprising: (a) a first disk sensor for sensing a loading of the first disk assembly in the apparatus by detecting the first capacity discriminate window thereof, and sensing a loading of the third disk assembly, the first disk sensor providing a binary output indicative of the presence or absence of the first capacity discriminate window, the first disk sensor comprising a first on-off switch having a switch actuator to be received in the window of the first disk assembly loaded in position within the apparatus and an output line, the first on-off switch being normally open and being connected between ground and the output line thereof; (b) a second disk sensor for sensing a loading of the second disk assembly in the apparatus by detecting the second capacity discriminate window thereof, and sensing the loading of the third disk assembly, the second disk sensor providing a binary output indicative of the presence or absence of the second capacity discriminate window, the second disk sensor comprising a second on-off switch having a switch actuator to be received in the window of the second disk assembly loaded in position within the apparatus and an output line, the second on-off switch being normally open and being connected between ground and an output line thereof; (c) a supply terminal connected to the output lines of the first and second switches; and (d) a disk detector circuit connected to the output lines of the first and second switches for detecting the loading of any one of the first, second and third disk assemblies in the apparatus on the basis of the binary outputs from the first and second disk sensors; (e) whereby the apparatus requires no sensor devoted exclusively for the detection of the loading of any one of the first, second and third disk assemblies in the apparatus.