| 摘要 |
PURPOSE:To avoid the alteration of wired logic of a servo pattern detecting logical circuit, by using a programmable read-only storage element as a servo pattern discriminating means. CONSTITUTION:Bit data on a bit pattern signal P are sequentially fetched to a shift register 10 with a clock signal C, they are converted into a parallel data consisting of 5 bits of SR0-SR4 and given to address input terminals A2-A6 of a PROM element 20. For example, ''01011'' is given as a bit data, and when this is judged as an index code IDX, the PROM element 20 transmits a logic ''111'' to a buffer register 30 as a signal W according to the program. Further, it is outputted on an index pulse signal (i) as a logic ''112''. When the bit data are given as ''10011'', it is judged as a pattern code OGB and logic 0, 1 is transmitted on output signals x, y. This signal is latched with the register 30 and outputted to code signals j, k as 0, 1. |
