using usb serial converter as VDIP? arduino
The VDIP1 is a packaging of FTDI's Vinculum embedded USB host, which gives a simple microcontroller some ability to interact with USB peripherals.

More common usb-serial converters from FTDI and others are USB-device interfaces, which have to be connected to a computer which has a USB host interface, and provide a legacy asynchronous serial interface for connecting to simple peripherals or small microcontrollers.  Because they contain a USB device interface rather than a USB host interface, they cannot be used to host USB peripheral such as a flash drive.

A number of modern microcontrollers have built in USB capability.  Typically this is device-only in the lower end models, but sometimes the high end models have an interface that can be configured to be either a USB host or a USB device.