When I follow the sequence below, my XCFP PROM is configured with a compressed MCS while the compression bit in the PROM is not correctly set. (If I use same sequence to unset a compressed MCS file, the FPGA programming will fail as well.)
1. Using an uncompressed MCS file, program the PROM.
2. In stand-alone mode, erase all the revisions in the device.
3. In iMPACT, double-click the device icon and assign it a compressed MCS file. (Do not select the device and delete it, and do not initialize the chain when changing the option from uncompressed to compressed.)
4. Program the PROM with the compressed MCS file.
5. Now, program the device: the DONE pin will not go High, and the INIT pin also stays Low.
To work around this problem, re-initialize the chain and perform an erase in stand-alone mode on the PROM. Reconfigure the PROM again, and the compression bit should be reset correctly. This problem is resolved in 6.3isp3 and later.