Browse Prior Art Database

Selective Display of Individual Keystrokes

IP.com Disclosure Number: IPCOM000062444D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Beauregard, GM: AUTHOR [+2]

Abstract

Most display terminal systems predetermine which piece of code displays the character associated with a particular keystroke. That is, when a key on the keyboard is pressed, either the terminal manager code will display it on the display screen (called local echo) or the application will display it after receiving notification via an interrupt (called application echo). Some systems allow the application to determine which method to use. The Terminal Mode Processor (TMP), in addition to allow either local or application echo, has uniquely defined the concept of selective echo of individual keystrokes. The application can modify what is called an echo map. In this map, there is one flag associated with each of the ANSI/ASCII character codes, single byte controls and control sequences.

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Selective Display of Individual Keystrokes

Most display terminal systems predetermine which piece of code displays the character associated with a particular keystroke. That is, when a key on the keyboard is pressed, either the terminal manager code will display it on the display screen (called local echo) or the application will display it after receiving notification via an interrupt (called application echo). Some systems allow the application to determine which method to use. The Terminal Mode Processor (TMP), in addition to allow either local or application echo, has uniquely defined the concept of selective echo of individual keystrokes. The application can modify what is called an echo map. In this map, there is one flag associated with each of the ANSI/ASCII character codes, single byte controls and control sequences. If the flag for a particular character is on, then the TMP performs local echo for the keystroke pressed. For example, if the lower case 'a' key is pressed and the echo flag is on for this ASCII character code, then the TMP will output an 'a' to the display if it so desires. The TMP only produces the interrupt reporting the event. In a similar fashion, single byte controls and control sequences can selectively be controlled. If the echo flag is off for the ANSI control sequence that moves the cursor left, then when the user presses the cursor left key, the TMP will not move the cursor. Again, only an interrupt will be generated. Selective ec...