A Berg adapter is used to supply power from the power supply, to the floppy drive. Some newer power supplies do not come with a berg due to low demand for floppy drives. You can purchase molex->berg adapters to fix this issue.
A Berg connector is a brand of electrical connector used in computer hardware. Berg connectors are manufactured by Berg Electronics Corporation of St. Louis, Missouri, a division of Framatome Connectors International.
Berg connectors have a 2.54 mm (=.100 inch) pitch, pins are square (0.64 mm x 0.64 mm = approx. 0.025 x 0.025 inch), and usually come as single or double row connectors.
Many types of Berg connectors exist. Some of the more familiar ones used in IBM PC compatibles …