4 ms·
Interesting that it does ECC on blocks of 64 byte instead of 64-bit, freeing up some of the bits in ECC RAM to be used for other things like extra tag bits.
by edwintorok 4y ago
Interesting that it does ECC on blocks of 64 byte instead of 64-bit, freeing up some of the bits in ECC RAM to be used for other things like extra tag bits.
- addaon 4y agoYeah. I've mentioned this before, but in DDR5 and beyond the nominal channel width goes from 64 bit to 32 bit -- and an ECC protected channel goes from 72 bit to 40 bit. (It would be possible to ECC protect a 32-bit channel with 39 bits, but the actual DRAM ICs come in multiples of 8 bits.) This means that applications that bond channels together and read/write/ECC-check in 64-bit chunks can have 8 unassigned bits per 80-bit read, while still ECC protecting the full width. I haven't seen any discussion of this capability, but it's super interesting to me.