1K 2.5V Dual Mode I2C Serial EEprom The 24LC21A is a 128 x 8-bit dual-mode Serial Electrically erasable prom designed to meet the plug-and-play requirements of today8217;s ... The 24LC21A is a 128 x 8-bit dual-mode Serial Electrically erasable prom designed to meet the plug-and-play requirements of today8217;s advanced monitors. The 24LC21A represents a simple, low-cost route to meeting the stringent standards 1K 2.5V Dual Mode I 2 C Serial EEprom