TW265473B - Three-level coding method for read only memory and device thereof - Google Patents

Abstract

A three-level coding method of read only memory, that is applicable to one three-level data array which has N-bit three-level cell storage code with two-bits as one set, and those which could not be assigned to set are viewed as independent bit, comprises the steps of: 1. performing three-level coding to one N-bit data, but when continuously meeting three or more than three sets of same sequence data, then reserving the first set of those same sequence data, and replacing the second set with one identification code as start code, replacing the third set with one identification code as end code, leaving the rest sets of same sequence data; 2. with the above coded N-bit three-level cell storage code through one sensing amplifier generating corresponding N-bit intermediate code, and with every two as one set, those which could not be assigned to set are viewed as one intermediate independent code; 3. inputting the above each set of intermediate code to one coding device; 4. when the intermediate codes of two adjoining two sets are different, the coding device output those intermediate data; 5. when one set of received data is confirmed as identification code, it is viewed as start code the first time, and in sequence replacing intermediate code of each set with intermediate code of each former set, then outputting; 6. until one set of received data is confirmed as identification code the second time, it is viewed as end code, and replacing intermediate code of the set with intermediate code of each former set, then outputting, in the same time, back to step 4, if there is no end code, then continuously replacing intermediate code of the set with intermediate code of each former set until end; 7. with the above intermediate code of each set processed by coding device, combined with another one independent intermediate code, as decoding source of decoding circuit.