An organic light emitting display device comprising: a first memory configured to store mobility compensation data (Dn), and configured to transmit the stored mobility compensation data when the organic light emitting display device is turned on; a data processing apparatus configured to classify the mobility compensation data (Dn) transmitted from the first memory into either low frequency compensation data (Da) or high frequency compensation data (Db) according to differences between adjacent data of the transmitted mobility compensation data (Dn), to encode the compensation data classified as the low frequency compensation data according to a low frequency encoding and the compensation data classified as the high frequency compensation data according to a high frequency encoding, wherein the encoded compensation data comprise a flag bit indicating whether the respective compensation data is the low frequency compensation data or the high frequency compensation data, and to transmit the encoded compensation data (dn), when the organic light emitting display device is turned on; a second memory configured to store the encoded data (dn) transmitted from the data processing apparatus and to update the stored encoded data, when the organic light emitting display device is turned on, and further configured to transmit the stored encoded data(dn')to the data processing apparatus when the organic light emitting display device is turned off; wherein the data processing apparatus is further configured to classify the encoded data transmitted from the second memory into either low frequency encoded data (da') or high frequency encoded data (db') according to a value of the flag bit of the encoded data transmitted from the second memory (dn'), to decompress the encoded data classified as the low frequency encoded data (da') according to a low frequency decoding and the encoded data classified as the high frequency encoded data (db') according to a high frequency decoding, and to transmit the decoded data (Dn')obtained by the decompression to the first memory, when the organic light emitting display device is turned off; wherein the first memory is further configured to update the stored mobility compensation data (Dn) using the decoded data (Dn'), when the organic light emitting display device is turned off. a first memory configured to store mobility compensation data (Dn), and configured to transmit the stored mobility compensation data when the organic light emitting display device is turned on; a data processing apparatus configured to classify the mobility compensation data (Dn) transmitted from the first memory into either low frequency compensation data (Da) or high frequency compensation data (Db) according to differences between adjacent data of the transmitted mobility compensation data (Dn), to encode the compensation data classified as the low frequency compensation data according to a low frequency encoding and the compensation data classified as the high frequency compensation data according to a high frequency encoding, wherein the encoded compensation data comprise a flag bit indicating whether the respective compensation data is the low frequency compensation data or the high frequency compensation data, and to transmit the encoded compensation data (dn), when the organic light emitting display device is turned on; a second memory configured to store the encoded data (dn) transmitted from the data processing apparatus and to update the stored encoded data, when the organic light emitting display device is turned on, and further configured to transmit the stored encoded data(dn')to the data processing apparatus when the organic light emitting display device is turned off; wherein the data processing apparatus is further configured to classify the encoded data transmitted from the second memory into either low frequency encoded data (da') or high frequency encoded data (db') according to a value of the flag bit of the encoded data transmitted from the second memory (dn'), to decompress the encoded data classified as the low frequency encoded data (da') according to a low frequency decoding and the encoded data classified as the high frequency encoded data (db') according to a high frequency decoding, and to transmit the decoded data (Dn')obtained by the decompression to the first memory, when the organic light emitting display device is turned off;