JPH01193894A - Crt display system - Google Patents

Abstract

PURPOSE:To increase the speed of plotting by providing a scrolling ring buffer and a fixed buffer for display of fixed information. CONSTITUTION:Graphic forms written in, for example, address 40000 or higher addresses in a ring buffer 10 pass round the an address 00000 side and are plotted, but this passing-round does not occur in a fixed buffer 9. Therefore, the start address is rewritten to scroll information in the ring buffer 10, and information in the fixed buffer 9 is displayed without scrolling. Thus, the lower half of a picture can be scrolled with the upper half fixed without writing data of the fixed data again in a new address at each time of scrolling, and images abundant in variation is quickly displayed.

Description

[Detailed description of the invention] [Industrial use The present invention relates to a CRT display RAM.

[Description of the prior art and its problems] Conventionally, in CRT systems that have a ring buffer to facilitate smooth scrolling, fixed information has to be rewritten each time the system is scrolled. There was a tendency for drawing to be slow.

The present invention ameliorates this drawback.

[Example] In this example, which shows the decoder section of the buffer in FIG.
When the T controller accesses with A19 set to H, it becomes a ring buffer when accessed with a fixed buffer.The CRT controller uses a controller that can set two display start addresses, and one start address is set on the ring buffer side. , and the other side is the fixed buffer side, it is possible to output both types of information at the same time.

In a ring buffer, a figure written at address 40000 or above is drawn around to address ooooo, but in a fixed buffer, no wrapping occurs. Therefore, while the information in the ring buffer is scrolled while rewriting the start address, the information in the fixed buffer can be displayed without being scrolled.

[Effect of the invention] In this way, for example, when scrolling the bottom half of the screen while fixing the top half of the screen, it is possible to realize this without having to rewrite the data in the fixed part to a new address every time you scroll. Displays with a wide range of changes can be displayed quickly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a CR7 display system according to the present invention, and FIG. 2 is a diagram showing a buffer decoder. 1 is the CPU on the main unit side, 2 is the CPU bus, 3 is the CR of 4 from CPLI
Data bus for T controller, 4 is CRT controller that controls display address, 5 is address bus from CRT controller to VRAM, 6 is CRT
A data bus from the controller to the VRAM, 9 a fixed buffer RAM that stores fixed information, 10 a ring buffer that stores data that needs to be scrolled, 7
．． 8 is each address decoder, and when the address is increased, the decoder 8 returns to O when the address exceeds a certain value, and access is made from the beginning.

Claims (1)

[Claims] A CRT display system that speeds up drawing by having a scrolling ring-shaped buffer and a fixed buffer that displays fixed information.