| 摘要 |
PURPOSE:To make the recording density of an inner and an outer circumferential track constant by making the recording and reproducing frequencies of the external circumferential and internal circumferential tracks different with regard to vertical magnetic recording and reproduction to and from a disk. CONSTITUTION:For 80KBPI recording to and reproduction from each track of an 8 inches floppy disk, the period frequency of an inner circumferential track is 6.12MHz, and that of a next track is 6.18MHz; and thus the frequency is increased by 60kHz, one by one, toward the outside. In the figure, an MC4344 is an IC for a PLL, an MC4324 is an IC for VCO, and an MC4316 is an IC for frequency division; and a 74LS273 is an IC for latching and varies the frequency division ratio of the MC4316 freely by a signal from a CPU. In this circuit, a signal with a 10kHz reference frequency is inputted and the frequency division ratio of the MC4316 is set to 1/306 to obtain 6.12MHz or to 1/309 to obtain 6.18MHz. |
