Video display card is a direct example of screen writing

Video Display Card An Example of a Direct Write Screen In the text DMA, the 4KB memory starts from the paragraph B000H as a memory, and many adapters (CGA, EGA, MCGA, VGA) that have both text modes and graphic mode use the 16KB memory started by B800h as a memory. In the memory, each character display position is assigned 2 bytes. The first byte (even address) contains a character's ASCII code that decodes it into a dot matrix mode on the screen via a character generator. The second byte (odd address) is attribute byte. Several domains of this byte controlled flicker, high brightness, and abnormal characteristics. Its characters are: At present, almost all PC video systems are based on 6845 video controller chips. The 6845 chip has 18 control registers, which are numbered from 0 to 17. Top 10 displays parameters in determining horizontal and vertical directions. Program designers don't pay attention. 10, 11 and 14, 15 registers store the shape and position of the light target. 12, 13 registers handle paging; 16, 17 registers report the pen position. Since the registers used by the programmer are paired, you need to write the address register, then write a register, then write the address register, then write the second register. Since the port number is the most convenient addressing in the use of Inc and DEC instructions. Example 9-1 Write the 11th and 12th registers of the 6845 chip (data in BX), read the full text, the technical area About μClinux transplantation on ARM7 S3C4510B Multi-looped into charge and discharge controller design Interrupt service routines for ARM embedded systems LED dimming engine design based on 8-bit MCU How to display Chinese characters, ASCII characters and color graphics on the LCD monitor

Our other product:

Professional lightning protection system for Tower	Professional FM Radio Station Equipment Package	FMUSER FU-1000C 1000W FM Transmitter With USB Audio Input Interface
FMUSER 200W FM Radio Broadcasting Package	Hotel IPTV Solution	FMUSER FSN-1000T V5.0 1KW FM Radio Broadcast Transmitter