| 摘要 |
1444513 Data processing system INTERNATIONAL STANDARD ELECTRIC CORP 22 Jan 1974 [26 Jan 1973] 02852/74 Heading G4A A data processing system used, e.g. to control a railway signalling system, comprises at least two redundant computers and, in normal operation, is arranged such that an output from a second one of the computers is fed to a first one of the computers for comparison therein with the output developed by that computer, if the comparison produced agreement the output is read into an output register from where it is read to the second or in the case where there are three computers, the third computer for comparison therein with the output of that computer, and if the comparison produces agreement the contents of the output register are gated as an output of the system. As described three computers R1, R2, and R3 normally operate in a triple redundant fashion and are assigned the functions of an output computer R1, a comparator computer R2, and a read back/check computer R3, any of the computers being able to perform any of the functions. Output computer R1 receives an output T2 from comparator computer R2 and compares it with its own output T1. If the outputs match the comparator computer output T2 is fed to output register A-Reg. If the outputs do not match R1 compares the output of R3, i.e. T3, with T2 and T1. If T2 and T3 or T1 and T3 match, T3 is fed to output register A-Reg, T1 or T2 being declared "erroneous" as appropriate. If none of the outputs match an alarm and interrupt are generated. Assuming T2 has been fed to A-Reg the contents of A-Reg are fed to read back/check computer T3 where they are compared with T3. If the comparison produces a match computer R1 is signalled and R1 enables the transmission of the contents of A-Reg, i.e. T2, to the system output. If the comparison does not produce a match R3 compares the contents of A-Reg with the outputs of R1 and R2, i.e. T1 and T2, received over lines L13 and L23. If the comparison produces a match R3 declares itself "erroneous" and enables the transmission of the contents of A-Reg to the system output. If the comparison does not produce a match R3 compares T1, T2, and T3 and if they all agree writes the result into -A Reg and repeats the read back check. Operation with only two computers, one performing the functions of the comparator and read back/check computers and the other that of the output computer, is described for when one computer continually differs from the other two, this computer being disconnected. It is stated that each output word from each computer may consist of like ordered bits from a plurality of control words, the control words being accumulated in appropriate controlled devices. The computers are arranged periodically to exchange and compare test data to determine if any are faulty. The computer outputs may be coded for error detection. |
