According to the documentation with ISSP (version 1.909), the device can be driven by a command of this form: issp cy8c29666 mycode.hex -p -n This does not seem to work. The green and red lights flash briefly, then go off; the status flashes for a bit (as it does when using the ISSP from its GUI), then (after not long enough time to do the programming), the red light comes on. Programming this part from the GUI works fine. The program appears to be returning an ERRORLEVEL of zero, supposedly signifying success. Also, BTW, the documentation says there is a file issp.bat with the distribution - that does not appear to be the case.