Replace Altera EPCS4 with M25P40

[Altera_Forum]

Hello folks, 

 We currently use epcs4 as altera FPGA's configuration device, but the price of epcs4 is quite expensive.  I found that ST's m25p40 can be used to replace the epcs4 in this link:http://fpgaforum.blogspot.com/2006/03/any-replacement-for-altera-epcs_19.html  And I found in some designs, m25p40 is used as the configuration device.  But in the datasheets of EPCS4 and m25p40, I found there is a difference about instruction "Read silicon ID" between them:  EPCS4: 1010 1011 (ABh) M25P40: 1001 1111 (9Fh)  I'm wondering whether there is any problems if using M25P40 to replace epcs4, as the "Read silicon ID" instructions are different.   Thanks!  Br,  Tang

[Altera_Forum]

You didn't read the M25P40 datasheet thoroughly. It's also supporting the 0xAB instruction. If I remember right, both chips have even the same manufacturer ID.