Originally Posted by Schoenfeld
Some fact: They claim that the MACH chips are still available - probably from Lattice. Not correct. Yes, something pin-compatible is available, but that's not voltage compatible. Also, it is highly questionable if the old Jedec files are compatible with the new chips, so aside from altering the PCB design, they might have to re-compile sources that they do not have.
That is (maybe) not entirely correct. The Blizzard 1260 uses MACH111s. The M4A5-Series is very similar and they are (mostly) pincompatible. They are powered with 5V too. The 3.3V equivalent would be the M4A3. The only major difference is that the MACH111 can use the dedicated JTAG-Pins as Input- or Clock-Pins whereas the M4A5-32/32 (which would be the equivalent in this example) can not. If the Blizzard uses this feature the M4A5s are incompatible.
Nevertheless migrating from MACH to M4A5 probably isn't trivial and I doubt the JEDECs are compatible without recompiling. Also the Blizzard 1260 uses different speedgrades of MACH111s, so timing issues could occur.