To configure a system using an SRAM-based device, each time you power on the device, you must load the configuration data. The EPCS device is a flash memory device that can store configuration data that you use for FPGA configuration purpose after power on. You can use the EPCS device on all FPGA that support AS x1 configuration scheme. For an 8-pin SOIC package, you can migrate vertically from the EPCS1 device to the EPCS4 or EPCS16 device. 

For a 16-pin SOIC package, you can migrate vertically from the EPCS64 device to the EPCS128 device. With the new data decompression feature supported, you can determine using which EPCS device to store the configuration data for configuring your FPGA. Example 1 shows how you can calculate the compression ratio to determine which EPCS device is suitable for the FPGA.