PROCESSOR, COMPUTER READABLE RECORDING MEDIUM, AND STORAGE DEVICE

1 . A processor comprising:

a first storage part that stores instructions of a program including sets of instruction groups, which sets are hierarchically structured;

a second storage part that stores an address value of the first storage part in which an instruction to be read next is stored;

a third storage part that includes storage areas respectively corresponding to hierarchical levels of the program; and

a control part that executes, when an instruction read from the first storage part is a call instruction that calls a different one of the sets of instruction groups, a control to store the address value in the second storage part in one of the storage areas of the third storage part that corresponds to one of the hierarchical levels with which the different one of the sets of instruction groups being executed is associated.

2 . The processor as claimed in claim 1 , further comprising a fourth storage part that store information that includes a result of an operation executed by the different one of the sets of instruction groups being executed and variables used thereby, wherein the control part stores the information stored in the fourth storage part in said one of the storage areas of the third storage part.

3 . A computer readable medium storing a program causing a computer to execute a process, the process comprising:

determining whether an instruction read from a first storage part which stores instructions of a program including sets of instruction groups hierarchically structured is a call instruction which calls a different one of the sets of instruction groups;

reading an address value of the first storage part which stores an instruction to be read next from a second storage part storing the address value, when the instruction is the call instruction to call the different one of the sets of instruction groups; and

storing the address value in the second storage part in one of storage areas of a third storage part respectively corresponding to hierarchical levels of the program,

the different one of the sets of instruction groups that includes the call instruction and is executed being associated with said one of the storage areas.

4 . A storage device comprising:

a storage medium that stores data magnetically;

a head that writes data to the storage medium and reads data from the medium;

an actuator that moves the head; and

a first processor that controls to write and read data in and from the recording medium; and

a second processor, the second processor including:

a first storage part that stores instructions of a program including sets of instruction groups, which sets are hierarchically structured,

a second storage part that stores an address value of the first storage part in which an instruction to be read next is stored,

a third storage part that includes storage areas respectively corresponding to hierarchical levels of the program, and

a control part that executes, when an instruction read from the first storage part is a call instruction that calls a different one of the sets of instruction groups, a control to store the address value in the second storage part in one of the storage areas of the third storage part that corresponds to one of the hierarchical levels with which the different one of the sets of instruction groups being executed is associated,

the second processor computing an amount of drive necessary to drive an actuator to move the head to a date writing position or a data reading position of the recording medium by referring to positional information stored in the storage medium.