System for display emulation by intercepting and changing control data stored in one of multiple temporary registers to suitable display control data

• US 5,179,690 A
• Filed: 09/29/1989
• Issued: 01/12/1993
• Est. Priority Date: 09/29/1988
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Ishikawa, Yasuo
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): TAYLOR, THOMAS
• Application Number:
  US07/414,955
• Time in Patent Office: 1,201 Days
• Field of Search: 364/200, 364/900, 395/162, 395/163, 395/164, 395/500, 395/112
• US Class Current: 703/24
• CPC Class Codes: G06F 3/14 Digital output to display device ; Cooperation and interconnection of the display device with other functional units

Abstract

A display emulating system in which control data for controlling a display are tentatively stored in a temporary register and modified to appropriate data suitable for the display, and then stored in an internal register within a controller for controlling the display.

Claims

1. A method of performing emulation comprising the steps of:

transmitting control data into an internal register within a controller of a display unit;

transmitting display data to be displayed on a displaying means;

transmitting an emulation enabling signal;

interrupting each initial transmission of control data into said internal register within the controller of the display unit in response to the emulation enabling signal;

activating, in response to the emulation enabling signal, through an interface control circuit, a gate control signal causing a command gate circuit to inhibit the internal register from writing the control data;

enabling, through an interface control circuit, the emulation enabling signal to activate a control section of an emulation circuit;

storing said control data transmitted through a bus in a temporary register within a group of temporary registers within the emulation circuit;

during the storing, providing command signals by a command decoder, including providing an address command to an address decoder, which stores the address within the group of temporary registers, providing an interface command to the interface control circuit, providing a flag command to an emulation flag, which provides information about the newly written-to temporary register, providing a temporary register command to the group of temporary registers, and providing a data gate command to a data gate circuit, which controls the flow of data to the temporary registers;

detecting which one of said temporary registers includes newly written data therein in accordance with the emulation flag;

determining whether the control data stored in the detected temporary register is suitable for the display unit through use of the command decoder and data gate circuit;

changing the control data stored in the detected temporary register to data suitable for the display unit when the stored data is not suitable for the display unit through use of the address decoder, command decoder and data gate circuit;

updating the commands sent by the command decoder to the address decoder, the data gate circuit and the emulation flag to reflect whether data has been changed;

sending a command from the command decoder to the interface control informing the interface control that data within the detected temporary register is now suitable for the display unit;

transferring the suitable control data stored in the detected temporary register into the internal register within the controller of the display unit; and

displaying the display data transmitted through the bus on the display unit under control of the controller in accordance with the suitable control data stored in the internal register.

2. A display emulating system comprising:

(a) means for displaying data;

(b) a bus means for transmitting the following information;

(b1) displaying data to be displayed on said displaying means,

(b2) control data for controlling said displaying means, and

(b3) an emulation enabling signal for signaling the start and the end of emulating operation;

(c) a display controller means comprising;

(c1) a group of internal registers storing the control data from said bus means,

(c2) memory storing the displaying data from said bus means, and

(c3) means for causing said displaying means to displaying the displaying data stored in said memory in accordance with the control data stored in the internal registers;

(d) an emulation circuit means comprising;

(d1) a group of temporary registers storing the control data from said bus means,

(d2) a register identifying means for identifying the register in which the control data are stored out of said group of temporary registers,

(d3) a destination switching means for directing the control data from said bus means to said group of temporary registers in said emulation circuit means or to said group of internal registers in said display controller means in accordance with the emulation enable signal, and

(d4) means for starting an emulation control means; and

(e) said emulation control means comprising;

(e1) means for triggering the interruption of each initial transmission of control data into the group of internal registers and storing said control data within the group of temporary registers,

(e2) means for identifying the register which stores the control data within said group of temporary registers by using said register identifying means in said emulation circuit means,

(e3) means for changing the control data to appropriate data when the control data stored in the identified register are not appropriate, and

(e4) means for transferring the appropriately changed control data from said group of temporary registers into said group of internal registers in said display controller means.