Three variable reference chart and calculator

A manually operable device for calculating total storage capacity of recording media comprising:

• a sleeve having a front surface and a rear surface;
• a sliding member positioned substantially within the sleeve, the sliding member having a first alignment portion and a second alignment portion;
• a first set of indicia printed on the sliding member representing a first set of values corresponding to file size or recording rate;
• a first opening formed in the front surface of the sleeve in alignment with the first set of indicia whereby a value for file size or recording rate is selectively exposed upon moving the sliding member within the sleeve;
• a first rotary member mounted on the sliding member within the sleeve, the first rotary member having a rotary alignment portion whereby the first rotary member is rotatable to align the rotary alignment portion with the first alignment portion of the sliding member;
• a second rotary member mounted on the sliding member in axial alignment with the first rotary member;
• a second set of indicia printed on the first rotary member representing a second set of values corresponding to the total number of recording media, the second set of values being selectively alignable with the second alignment portion of the sliding member whereby a second one of the second set of values is selected;
• a third set of indicia printed on the second rotary member representing a third set of values corresponding to the storage capacity of each of the recording media, the second rotary member being rotatable to move the third set of indicia proximate the rotary alignment portion of the first rotary member whereby one of the third set of values is selected;
• and
• a second opening in the sleeve in alignment with indicia representing predetermined values for the total storage capacity of the recording media, each total storage value corresponding to selected combinations of the first, second and third values wherein each total storage value is the product of selected ones of the first, second and third values.

A method of manually determining the total storage available on a data storage media made up of a plurality of storage disks comprising the steps of:

• calculating a set of values corresponding to total storage time dependent on a first range of disk sizes, a second range of data recording rates, and a third range of total numbers of disks;
• providing a sleeve having a front surface and a rear surface, the front surface having a first opening and a second opening formed therein;
• providing a sliding member positioned substantially within the sleeve, the sliding member having a first alignment portion and a second alignment portion, the sliding member having a first set of indicia printed thereon in a position which is exposable through the first opening and a second set of indicia printed thereon in a position which is exposable through the second opening, wherein the first set of indicia corresponds to the second range of data recording rates and the second set of indicia corresponds to the calculated values of total storage time;
• providing a first rotary member mounted in the sliding member within the sleeve, the first rotary member having a rotary alignment portion and having a third set of indicia printed thereon which correspond to the third range of total numbers of disks;
• providing a second rotary member mounted on the sliding member in axial alignment with the first rotary member, the second rotary member having a fourth set of indicia printed thereon which correspond to the first range of disk sizes;
• rotating the first rotary member until the rotary alignment portion thereof is adjacent to the first alignment portion of the sliding member;
• selecting a value for disk size from the first range by rotating the second rotary member while maintaining the first rotary member in alignment with the sliding member;
• subsequent to selecting disk size, moving the sliding member until a desired recording rate from the second range is exposed through the first opening;
• subsequent to selecting disk size and recording rate, selecting a value for the number of disks from the third range by simultaneously rotating both the first and second rotary members while maintaining the position of the sliding member;
• and
• observing the value of the storage time indicated through the second opening.