| 摘要 |
PURPOSE:To attain accurate communication by forming a check sum data at each block at the transmission side, transmitting it with a normal data, forming a check sum data from a received data at the reception side, returning the received data when the both are coincident and checking the propriety of the said data at the transmission side. CONSTITUTION:An R-ROM writer is provided to the 1st and 2nd communication stations as shown in figure. A code [figure (a)] stored in an EP-ROM17 or the like is added with a check sum data DC. The data DC is given by taking two sets of exclusive OR of even and odd number orders of a low-order 4-bit of an address DA and a data DD in one text and used for the check of a horizontal parity. In receiving a data for one text added with the data DC at the 2nd station, the check sum data for the DA, DD is taken, it is compared with the received DC, and when they are coincident, the said data is returned. The 1st station compares the preceding transmitted data with the returned data and when they are coincident, the next test is transmitted. |
