Display managing arrangement with a display memory divided into a matrix of memory blocks, each serving as a unit for display management

• US 4,920,504 A
• Filed: 09/17/1986
• Issued: 04/24/1990
• Est. Priority Date: 09/17/1985
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Sawada, Hachiro, Fujitsu, Tadashi, Honma, Hideaki, Takahashi, Ken-ichi
• Primary Examiner(s): CLARK, DAVID
• Application Number:
  US06/908,432
• Time in Patent Office: 1,315 Days
• Field of Search: 340/726-728, 340/749, 340/798, 340/799, 340/750, 364/518, 364/521
• US Class Current: 345/573
• CPC Class Codes: G09G 2360/122 Tiling
• CPC Class Codes: G09G 5/346 for systems having a bit-mapped display memory
• CPC Class Codes: G09G 5/39 Control of the bit-mapped memory

Abstract

In a display managing arrangement comprising a display memory and a display memory controller for accessing the display memory to display a selected area of an image datum with the selected area scrolled on the image datum or otherwise subjected to management, the display memory is divided into memory blocks arranged as an N-row M-column matrix. Each memory block is for use as a unit of the management and is divisible into memory elements arranged as an n-row m-column matrix. When the memory elements of the display memory are assigned with serial memory element addresses along each row of the memory elements of the display memory and then along a next column-wise downward row, the memory controller may access the memory elements of selected ones of the memory blocks in block parallel by specifying the serial memory element addresses for each memory block on the one hand from a least memory element address in the memory block under consideration consecutively to the serial memory element address which is equal to the least memory element address plus the number m less one. On the other hand, the serial memory element addresses are specified discretely along one of the m columns by adding products of a step value mM and multipliers variable from zero to the number n less one to one of the serial memory element addresses that is congruent with the least memory element address modulo the step value. On storing the selected area in the display memory, the image datum may likewise be accessed.

Claims

1. In a display managing arrangement comprising a display memory for memorizing an image part of an image datum and a display memory controller for controlling said display memory to specify a display part on said image part, said display memory comprising a plurality of memory blocks arranged as a matrix of rows, N in number, and columns, M in number, each of said memory blocks comprising a plurality of memory elements arranged as another matrix of rows, n in number, and columns, m in number, and having serial memory element addresses, respectively, said serial memory element addresses consecutively increasing along each row of the memory elements of said display memory and stepwise increasing by a block step value mM between two column-wise consecutive ones of said memory elements, wherein said display memory controller comprises:

a determinant register for storing signals representative of the numbers m and n, said step value, a block column range, and a block row range, said block column and row ranges specifying specific ones of said memory blocks as specific memory blocks by the numbers M and N;

a top address register for storing a signal representative of a top address for each of the memory blocks of said display memory, said top address being the serial memory element address which is least among the serial memory element addresses of said each of the memory blocks;

a first address generator coupled to said determinant register and to said top address register for generating a first address signal representative of a first portion of said serial memory element addresses for each of said specific memory blocks, said first portion being consecutive from said top address to one of said serial memory element addresses that is equal to said top address plus m less one;

a second address generator coupled to said determinant register and to said top address register for generating a second address signal representative of a second portion of said serial memory element addresses, said second portion being congruent modulo said block step value with the top address plus integral multiples of said step value, said integral multiples being from zero to the number n less one; and

accessing means connected to said first and said second address generators and to said display memory for accessing the serial memory element addresses of each of said specific memory blocks.

2. A display managing arrangement as claimed in claim 1, wherein said specific memory blocks are for storing said display part.

3. A display managing arrangement as claimed in claim 1, wherein said display memory controller accesses said image datum to store a selected region thereof in said display memory as said image part, said image datum being divided into a plurality of block data arranged as a matrix of columns, X in number, and rows, Y in number, each block datum being divided into a plurality of image elements arranged as a matrix of m columns and n rows, the image elements of said image datum being assigned with serial image element addresses, respectively, said image element addresses consecutively increasing along each row of the image elements of said image datum and stepwise increasing by a data step value mX between two column-wise consecutive ones of said image elements, wherein:

said determinant register further stores signals representative of another product nN, said data step value, an image column range representing said block column range, and an image row range representing said block row range, said image column and row ranges specifying specific ones of said block data as specific block data;

said top address register further stores signals representative of a row-wise and a column-wise start address for each of said specific block data, and row-wise start address being the serial image element address which is least among the serial image element addresses of the image elements of the block datum under consideration, said column-wise start address being congruent with said row-wise start address modulo said data step value;

said first address generator generating said first address signal representative of a first portion of said serial image element addresses for each of said specific block data, said first portion of the serial image element addresses being consecutively from said row-wise start address to one of said serial image element addresses that is equal to said row-wise start address plus the number m less one;

said second address generator generating said second address signal representative of a second portion of said serial image element addresses, said second portion of the serial image element addresses being equal to said column-wise start address plus multiples of said data step value;

said accessing means comprising;

a first address compensating circuit coupled to said determinant register and responsive to said first address signal for calculating compensated row-wise addresses by subtracting an integral multiple of the number m from at least a portion of said first portion of the serial image element addresses so that said compensated row-wise addresses do not exceed the product mM;

a second address compensating circuit coupled to said determinant register and responsive to said second address signal for calculating compensated column-wise addresses by subtracting an integral multiple of the number n from at least a portion of said second portion of the serial image element addresses so that said compensated column-wise addresses do not exceed the product nN; and

output means responsive to said compensated row-wise and column-wise addresses for calculating the serial image element addresses for each of said specific block data to produce an additional output address signal representative of the last-mentioned serial image element addresses.

4. A display managing arrangement as claimed in claim 3, wherein said specific memory blocks are the memory blocks of said display memory.