Method and circuit arrangement for storing dictations in a digital dictation machine

摘要

It is known to digitally store speech signals in a semiconductor memory. For storing speech signals, much storage space is required, and thus for longer recordings, for example dictations, a very large semiconductor memory is required. This is advantageously implemented by a so-called flash-memory. However, its contents can only be erased in large sections at a time, and thus minor changes, such as partial erasures and insertions, are not possible. The total available memory is subdivided into clusters and a table of contents is created in which the stored files and the state occupation of each cluster are stored, as this is known from the DOS file manager. Moreover, an information which indicates which cluster is the following cluster of a file is stored for each cluster in a file-allocation-table. This process allows erasures or insertions to be carried out by altering the indications in the file-allocation-table to the following cluster. In this manner, clusters may be both inserted into and removed from a file. In addition, information on each cluster includes the number of speech frames stored in the cluster and from which address the first speech frame is stored. It is thus possible to logically remove from the file individual speech frames which form the smallest subdivision of the stored speech signal at the beginning or end of a cluster, without having to run an erasing process.