I want to write data from the 8052 ... to USB Flash memory

Based on 1) the processors Philips state are 'good' for their USB host chip and 2)Cypress not using '51 architecture for their HOST USB chips I conclude that the '51 does not have the muscle to be a USB host driver.
Soon I will receive from Cypress the code for a USB host (with a non '51 processor) that has a SPI interface to my '51 network. Cypress intend to develop this a bit further and then release it as an appnote.

Erik