A 312 KB PDF covering the 24LC21 serial EEPROM, with the -1 suffix probably marking a separate edition or part one of the documentation. The 24LC21 stores monitor EDID data and speaks the VESA DDC protocol over I2C lines. Expect pin assignments, supply range, timing diagrams and the mode-switching description. Use it when tracing the SDA and SCL lines from a VGA, DVI or HDMI connector, or when preparing to rewrite the chip with a programmer. Back up the original contents before any write and compare the part marking.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
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The standard format for schematics, block diagrams, power-sequence charts and service manuals.