Antwoord op "What is a HDMI port?"The HDMI port is used to transfer HD video and multi-channel audio over a single cable.
Antwoord op "Can I upgrade my RAM emory"Yes, you can. According to the Acer website the 5742 will support up to 8Gb of ram.
Antwoord op "My laptopt can't boot"Try removing the battery and the power cord. Hold the power button on for a few seconds. Insert battery and power cord then power on the system and see if that helps.