| 摘要 |
1,264,195. Data processing. INTERNATIONAL BUSINESS MACHINES CORP. 10 July, 1969 [15 July, 1968], No. 34811/69. Heading G4A. A data processing system includes a functional unit for performing logical operations in which data normally supplied to a first part of the unit is supplied to another part on detection of an error in the first part. An adder normally receives an already-parity-checked 4-byte word parallel by bit, but if a parity error is detected in any byte. position of the output of the adder, the word is passed through. again, a half-word at a time using the error-free half of the width of the adder if either half is error-free or a byte at a time using the (first) error-free quarter of the width if neither half is error-free but at least one quarter is. (As a modification, two error-free quarters may be used.) The data was saved in auxiliary registers in case of error, and is passed from the registers in the correct position using inter-register transfer with shift by gating. The adder output is reconstituted into one-word parallel form. The above operations can be achieved by inhibiting the output of a microprogramme store controlling the system, on detection of error, so that the next microinstruction is taken from address zero, and using latches, set to indicate which halves and quarters of the adder are error-free (if any). If a further error occurs the system may adjust the data flow width again. The latches are reset when the whole word has been processed. If a predetermined. number of errors have been counted, this reset is inhibited, and an error signal is forced on any further attempt to use the adder, since presumably the error is not transient. Thus no further attempt is made to use the full data flow width. In a second embodiment, the unit is a parallel adder with two inputs, each normally receiving a word in parallel, but the data flow width can be halved as above on error. A carry trigger is provided for each half. Error correction facilities could be provided, data flow width reduction being used only in the case of uncorrectable errors. Processing of the word need not be restarted at the beginning on error: the data passed through the error-free portions could be retained and only the other data recycled. |
