EP0238113A2 - Datenanzeige - Google Patents

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Publication number
EP0238113A2
EP0238113A2 EP19870200221 EP87200221A EP0238113A2 EP 0238113 A2 EP0238113 A2 EP 0238113A2 EP 19870200221 EP19870200221 EP 19870200221 EP 87200221 A EP87200221 A EP 87200221A EP 0238113 A2 EP0238113 A2 EP 0238113A2
Authority
EP
European Patent Office
Prior art keywords
data
display
character
memory
pixel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP19870200221
Other languages
English (en)
French (fr)
Other versions
EP0238113A3 (de
EP0238113B1 (de
Inventor
David Edward Penna
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Philips Electronics UK Ltd
Koninklijke Philips NV
Original Assignee
Philips Electronics UK Ltd
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Philips Electronics UK Ltd, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Electronics UK Ltd
Publication of EP0238113A2 publication Critical patent/EP0238113A2/de
Publication of EP0238113A3 publication Critical patent/EP0238113A3/de
Application granted granted Critical
Publication of EP0238113B1 publication Critical patent/EP0238113B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G5/00—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
    • G09G5/22—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators characterised by the display of characters or indicia using display control signals derived from coded signals representing the characters or indicia, e.g. with a character-code memory
    • G09G5/24—Generation of individual character patterns

Definitions

  • the invention relates to a method of storing character data in a background memory of a digitally operable data display apparatus for displaying as an entity on a screen of a display device a quantity of data which is represented by digital codes stored in a display memory, the displayed data being in the form of discrete pixels or dots, each of which has its colour and/or luminance defined by a respective digital code in the display memory at a location corresponding to the position of the pixel in the display, the apparatus including a processor for controlling digitally the storage, selection and display of data.
  • the invention further relates to a method of displaying data in a digitally operable data display apparatus for displaying as an entity on a screen of a display device a quantity of data which is represented by digital codes stored in a display memory, the displayed data being in the form of discrete pixels or dots, each of which has its colour and/or luminance defined by a respective digital code in the display memory at a location corresponding to the position of the pixel in the display, the apparatus including a processor for controlling digitally the storage, selection and display of data.
  • This invention still further relates to digitally operable data display apparatus for displaying as an entity on a screen of a display device a quantity of data which is represented by digital codes stored in a display memory, the displayed data being in the form of discrete pixels or dots,each of which has its colour and/or luminance defined by a respective digital code in the display memory at a location corresponding to the position of the pixel in the display, the apparatus including a processor for controlling digitally the storage, selection and display of data.
  • the display produced by apparatus of the above type is termed a bit-map display, and is, for example, a 320 ⁇ 250 resolution dot matrix colour display which may be displayed on the screen of a CRT (cathode ray tube) or other display device.
  • a CRT cathode ray tube
  • the digital codes stored in the display memory are accessed repeatedly by the processor to update the display in a recurrent cycle of scanning lines which may be produced with or without interlaced field scanning.
  • a data display apparatus of the above type is to provide comprehensive and visually aesthetic text displays, it is usually a requirement that data for a large number of different character fonts is provided in a background memory and the data for individual characters selected for display is read from the background memory and written into the display memory.
  • the invention provides a method of storing character data as set forth in the opening paragraph characterised in that the method consists of generating a machine code sub-routine as the data for each of a plurality of characters, and storing the machine code sub-routines at predetermined locations in the background memory.
  • the main advantage that the present invention achieves is the significant saving in the number of processor operating steps that are required to write the data for a character into the display memory. Therefore, for a given speed of operation of the processor, the contents of the display memory can be updated for the display of a new page of text far more quickly than in apparatus where character data is stored in the background memory in bit-map form.
  • the invention also extends to a memory device containing character data which are stored as machine code sub-routines.
  • a memory device may be a floppy disk or the like, or a read-only memory, in which a large number of different character data can be provided in a simple and relatively inexpensive way.
  • the invention further provides a method of displaying data as set forth in the second paragraph characterised in that the method comprises storing character data in the background memory as a machine code sub-routine for each of a plurality of characters, selecting a character for display, selecting the position of the character on the display screen, causing the appertaining sub-routine to be run to write the pixel data for the character in bit-map form in the appropriate memory location in the display memory, and causing the data in the display memory to be displayed on the display screen.
  • the invention still further provides a digitally operable data display apparatus as set forth in the third paragraph characterised by means for storing character data in a background memory in the form of a machine code sub-routine for each of a plurality of characters, means for selecting a character for display, and means for causing the sub-routine appertaining to the selected character to be run to write the pixel data for the character in bit-map form in the appropriate memory location in the display memory.
  • the data display apparatus shown in Figure 1 comprises a display device 1, a display generator 2, a processor 3, a background memory 4, a display memory 5 and user interface apparatus 6 and 7.
  • the display device is suitably a colour television monitor which is connected to receive R, G, B, video signals from the display generator 2. These R, G, B, video signals are produced in the display generator 2 by three digital-to-analogue converters 8, 9 and 10, respectively.
  • the display generator 2 also included a colour look-up table 11 which is suitably a read/write memory and is responsive to dot information received from the display memory 5 over a bus 12 to produce digital signals for driving the converters 8, 9 and 10.
  • a display timer 13 in the display generator 2 provides line and field synchronisation signals LS and FS for the television monitor 1 over a connection 14.
  • the timer 13 also provides over a connection 15 timing signals T for controlling the transfer of dot information from the display memory 5 to the colour look-up table 11.
  • the display memory 5 is a random-access memory which has a capacity for storing dot information for at least one display frame.
  • the dot information comprises digital codes composed of one or more bits per dot to be display, depending on the range of colours afforded by the colour look-up table 11.
  • a combined address-data bus 16 interconnects the display generator 2 and the display memory 5 with the processor 3.
  • the background memory 4 which is also at least partially a random-access memory, is also connected to the address-data bus 16.
  • the background memory 4 may also have a read-only memory part of which contains permanent program data for controlling the "house-keeping" operations of the processor 3.
  • the user interface apparatus comprises a keyboard data entry device 6 and a writing tablet 7. Such interface apparatus is well-known in the art and specific details thereof are unnecessary for an understanding of the present invention.
  • the processor 3 can be a commercially available microprocessor, for instance the Signetics S68000 ⁇ p.
  • This character data comprises a 5 ⁇ 5 bit matrix CH in which logic '1's represent the character shape and logic '0's represent background data. If the background memory contains memory locations of 8-bit bytes, as is common, then five such bytes b 1 to b 5 are required to store the character data. Consequently the byte area signified at B is redundant in this case.
  • the programme step will take of the order of 6-8 instructions, for each bit, so that a total of up to 200 instructions will be necessary to write the data for the cross (+) into the display memory.
  • Figure 4 shows the machine code instructions that are required to write the cross (+) into the position CP by means of a method according to the invention.
  • data which identifies the colour that the cross (+) is to be displayed in is entered into a first register (D0).
  • Data which identifies a base dot position for the character position is then entered into another register (A0).
  • the background memory includes an address table for each possible character shape that can be displayed. When a character is selected by keyboard operation, the selected character is identified and the address for the character data is read from the address table. This character data, which is in the form of machine coded instructions is then accessed by the processor to write the character data into the display memory.
  • the instruction (1) in Figure 4 provides the character colour.
  • the instruction (2) provides the base dot address which is pixel bit position 82 in the bit-map display memory BM/DM.
  • the remaining instructions (3) to (11) cause the processor to step in turn to each of the dot positions which are to contain a pixel for the character shape.
  • the machine code instructions can also be arranged to write into the display memory the character data starting from a base dot position which is the first actual pixel position for a character.
  • Figure 5 shows an example of these alternative machine code instructions.
  • the register A0 is initially set to pixel position 148, and instruction (2) writes in a pixel at that position.
  • Instructions (3) to (6) then successively write into pixel positions 132, 116, 100 and 84.
  • Different instructions (7) to (10) then write into the remaining pixel positions 114, 115, 117 and 118.
  • Figure 6 shows the character W written into the bit map display memory BM/DM, the character W having its base position CP at pixel 177 in the memory.
  • Figure 7 shows the machine code instructions that are required to write the character W into the position CP (177).
  • data which identifies the colour that the character W is to be displayed in is entered into a first register (D0).
  • Data which identifies a base dot position for the character position is then entered into second register (A0).
  • the background memory includes an address table for each possible character shape that can be displayed. When a character is selected by keyboard operation, the selected character is identified and the address for the character data is read from the address table. This character data, which is in the form of machine coded instructions is then accessed by the processor to write the character data into the display memory.
  • the instruction (1) in Figure 8 provides the character colour.
  • the instruction (2) provides the base dot address which is pixel bit position 177 in the bit-map display memory BM/DM.
  • the remaining instructions (3) to (34) cause the processor to step in turn to each of the pixel dot positions which are to contain a pixel for the character shape.
  • Figures 8 and 9 are flow diagrams which illustrate the generation of characters for display on the display apparatus.
  • reference 200 represents the start of the process and reference 201 represents the selection of the character to be displayed, its colour, and its base position (equivalent to CP in Figures 2 and 6).
  • Reference 202 represents the selection of the corresponding character machine code sub-routine from the background memory.
  • Reference 203 represents the running of the machine code sub-routine to cause the selected character to be read in bit-map form into the display register.
  • Reference 204 represents the display of the character on the display screen from the information in the bit-map display.
  • Reference 205 denotes the end of the process.
  • Figure 9 illustrates the transfer of the character data from the background memory to the bit map memory BM/DM under the control of a selected machine code sub-routine.
  • the colour and base position having been specified (reference 201, Figure 8) the running of the sub-routine accesses first the distance, in number of pixels, from the base pixel to the first active pixel dot, box 302.
  • This combined with the base pixel address comprises the display memory address and the code in register DO representing the pixel colour is read into the location in the display memory represented by that address,box 303. If that is the final active pixel for the selected character then the process ends, box 306.
  • the distance in number of pixels from the base pixel to the next active pixel dot is accessed, box 305.
  • the code in register DO representing the pixel colour is read into the display memory location represented by the new distance and base address. This sequence is repeated until the final pixel element has been written, box 304.
  • each sub-routine the bit-mapped version of the character is examined and the distance of each active dot in the character from the base dot is calculated.
  • the sub-routine then consists of stepping through addresses of the active dots to read the colour information into the bit-mapped display memory.
  • the sub-routine effectively comprises a list of machine code instructions each of which contain the distance, in terms of number of pixels, to the next active dot of the individual character with respect to a base dot of the matrix. It will be seen that instructions (1) and (2) of Figures 4, 5 and 7 are essentially the same and consequently these do not need to be stored with the separate character sub-routines but can be part of the display controlling program.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Controls And Circuits For Display Device (AREA)
  • Digital Computer Display Output (AREA)
EP19870200221 1986-02-17 1987-02-12 Datenanzeige Expired - Lifetime EP0238113B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB08603850A GB2186766A (en) 1986-02-17 1986-02-17 Character display apparatus
GB8603850 1986-02-17

Publications (3)

Publication Number Publication Date
EP0238113A2 true EP0238113A2 (de) 1987-09-23
EP0238113A3 EP0238113A3 (de) 1991-07-17
EP0238113B1 EP0238113B1 (de) 1994-11-23

Family

ID=10593182

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870200221 Expired - Lifetime EP0238113B1 (de) 1986-02-17 1987-02-12 Datenanzeige

Country Status (4)

Country Link
EP (1) EP0238113B1 (de)
JP (1) JPH083704B2 (de)
DE (1) DE3750766T2 (de)
GB (1) GB2186766A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110675800A (zh) * 2019-11-07 2020-01-10 广东乐心医疗电子股份有限公司 显示屏驱动方法和装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2007413A (en) * 1977-10-31 1979-05-16 Diab K M Processing Arabic-Farsi languages

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2007413A (en) * 1977-10-31 1979-05-16 Diab K M Processing Arabic-Farsi languages

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110675800A (zh) * 2019-11-07 2020-01-10 广东乐心医疗电子股份有限公司 显示屏驱动方法和装置

Also Published As

Publication number Publication date
EP0238113A3 (de) 1991-07-17
JPH083704B2 (ja) 1996-01-17
DE3750766T2 (de) 1995-06-22
GB8603850D0 (en) 1986-03-26
GB2186766A (en) 1987-08-19
EP0238113B1 (de) 1994-11-23
JPS62249188A (ja) 1987-10-30
DE3750766D1 (de) 1995-01-05

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