| 摘要 |
PURPOSE:To prevent effectively a game machine from unfairness due to a copy of a card by carrying out the parity check of magnetic data and the parity check of codes read out of a security mark in a card reader to reject immediately cards having parity errors from the card reader. CONSTITUTION:The exclusive OR operation on a byte basis for magnetic data, ETX and LRC is performed to be successively put into a work area, and the check of the LRC is carried out by judging whether or not the operation result is '0'. A parity bit is masked since it is not subjected to the LRC inspection. The parity check is carried out for respective data on a byte basis to be repeated as many times as the number of the data. In the inspecting process of security, the security code read out by a security sensor and stored in a security buffer is put in a shift register, and the parity check is carried out by counting the number of bits set to '1'. |
