I've just started using the KEIL product with Cypress EZ-USB FX development kit. The EZUSB core supports a sort of bootstrap loader on the I2C interface. If you use B6 for the first byte in a serial eeprom device, it looks like the core will copy records of a certain format into memory. However, it limits 8051 program/data space that can be written to 0x1b3f. Two questions. 1) why the limitation? The core also supports a specific vendor request (bRequest A0, Control EP0 IN and OUT) that can write or read to seemingly any external memory space. 2) Is it possible to write a loader app that can be loaded by the core at power up, interrogate the rest of the I2C device, load external ram and then transfer control to exteral program now loaded? The idea being that even though it's easy to soft load the EZ-USB device, you could run a whole program loaded from the I2C serial eeprom.