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Display Control Circuit

IP.com Disclosure Number: IPCOM000062089D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Maezawa, Y: AUTHOR

Abstract

The display control circuit for performing a keyed function in accordance with the operating status of the display workstation includes a status register which stores bit patterns representing the operating status of the display workstation, a condition table which stores bit patterns of keyed internal code, and a function subroutine vector table which selects the function of the display workstation in response to ANDed results of the bit pattern of the operating status and the bit pattern of the internal code. Each key on the keyboard of the display workstation is assigned to various functions. One of the functions is selected in accordance with the shift status, e.g., upper shift, lower shift, control shift, etc., which are designated by shift key.

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Display Control Circuit

The display control circuit for performing a keyed function in accordance with the operating status of the display workstation includes a status register which stores bit patterns representing the operating status of the display workstation, a condition table which stores bit patterns of keyed internal code, and a function subroutine vector table which selects the function of the display workstation in response to ANDed results of the bit pattern of the operating status and the bit pattern of the internal code. Each key on the keyboard of the display workstation is assigned to various functions. One of the functions is selected in accordance with the shift status, e.g., upper shift, lower shift, control shift, etc., which are designated by shift key. The shift status is stored in register 1, and is supplied to table 2 along with scan code generated by the depressed key. Both the shift status and the scancode are used as addresses for accessing the table 2. The accessed entity of the table 2 stores internal code which represents the selected function of the depressed key in accordance with the shift status. Status register 3 stores bit patterns, which represent the operating status of the display workstation, which is determined by command from the host system, the condition of the communication line, etc. It is assumed that the status register 3 has four stages. The first stage indicates if the workstation is in the key-locked condition, the second stage indicates if the workstation is in the emulation mode, the third stage indicates if the workstation is in t...