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Error Recovery in a Word Processing Terminal

IP.com Disclosure Number: IPCOM000052282D
Original Publication Date: 1981-May-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 3 page(s) / 42K

Publishing Venue

IBM

Related People

Kerigan, SC: AUTHOR

Abstract

Word processing terminals commonly use a volatile store to edit a docum This article describes how the word processing system itself can recover from loss of text within the volatile store by means of a non-volatile keystroke store which stores every keystroke made by the operator from the time the document is fetched into the volatile edit store until the edited document is finally stored.

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Error Recovery in a Word Processing Terminal

Word processing terminals commonly use a volatile store to edit a docum This article describes how the word processing system itself can recover from loss of text within the volatile store by means of a non-volatile keystroke store which stores every keystroke made by the operator from the time the document is fetched into the volatile edit store until the edited document is finally stored.

In the drawing, text store 1 of non-volatile storage, typically a magnetic disc or tape store, contains documents. By means of word processing terminal 2, typically consisting of a display screen and a keyboard, an operator can fetch a document from text store 1 into edit store 3 which consists of volatile storage, for example, random-access semiconductor memory. The document stored in edit store 3 is displayed to the operator at terminal 2 who can then edit the document using the keyboard. Each keystroke made by the operator is processed (interpreted) by keystroke processor 4 and the required changes (insertion, deletion, formatting, etc.) made to the document in edit store 3 under control of text processor 5 via the supervisory program 7. When editing is complete, the document can be refiled in text store 1.

Because edit store 3 is volatile, it can become corrupted due to two main reasons: firstly, a failure, either hard or soft, in volatile store 3 (i.e., a bit failure in a fixed location RAM (random-access memory) or a loss of power to the store), and, secondly, a miskeying by the operator. This is due to the fact that text processor 5 may take more than one keystroke time (time between keystrokes may be as low as 10 ms) to process the document, and hence the operator may not know which keystroke caused the corruption (corruption in these circumstances implies a modification to the document which the operator does not recognize). Hence, the operator does not know which corrective keystrokes are required to restore the document back to its desired state.

To avoid these problems, which may be considerable if the operator has been updating a large document and has been editing for a couple of hours, keystroke store 6 is used to store every keystroke made by the operator between the time the document is fetched from text store 1 and the edited document is stored in text store 1. Keystroke...