Portable semiconductor data storage device

Claim 1

A portable semiconductor data storage device comprising: data word storage means for storing data words each data word having one of a first data bit length and a second data bit length, wherein the second data bit length is longer than the first data bit length; redundant word storage means for storing redundant words corresponding to the data words, the redundant words having a first redundant word length and a second redundant word length respectively corresponding the first data bit length and the second data bit length, the redundant words of the first and second redundant word lengths containing error detection and error correction data, wherein the second redundant word length is longer than the first redundant word length; a timing generating circuit, coupled to an external control bus, for generating a first/second length switch-over signal indicative of whether a data word has the first data bit length or the second data bit length; error detection means, coupled to the data word storage means, the redundant word storage means, and the timing generating circuit, for receiving the first/second length switchover signal and for detecting an erroneous bit in a data word stored in the data word storage means using that data word and the corresponding redundant word stored in the redundant word storage means and from the first/second length switch-over signal; and error correction means for correcting the erroneous bit detected by the error detection means.