fzabkar wrote:

AISI, the two READ ID commands would enable us to identify the lines corresponding to data bits 0, 3, 5 and 6. There would be two possible line combinations for data bits 4 and 7, and two combinations for bits 1 and 2. The final result would be 4 possible combinations for the real flash ID.

I think I made a mistake. ISTM that it should be possible to do better than that.

https://user.eng.umd.edu/~blj/CS-590.26/micron-tn2919.pdfAttachment:

READ_ID_90h_20h.gif [ 18.78 KiB | Viewed 1580 times ]
There are 28 possible combinations of lines 0 - 7 corresponding to the 90h/00h READ ID command. One combination will produce a 4-byte/5-byte ID. This identifies the two lines corresponding to data bits 4 and 7, but not necessarily in that order.

There are now 6 remaining lines, one of which corresponds to data bit 5. We now execute the 90h/20h READ ID command until we get a result. This identifies data bit 5, and it gives a result which we know is an "ONFI" text string.

Comparing "ONFI" bytes 0 and 1 gives us the line corresponding to data bit 0.

Now that we have identified data bits 0, 4, 5, 6 and 7, it only remains to find bits 1, 2, and 3.

Comparing the "F" and "I" bytes gives us the line corresponding to data bit 1.

Comparing the "N" and "F" bytes now gives us the lines corresponding to data bits 2 and 3.

Now we know all the data bits except for 4 and 7, but this leaves us with only two possible combinations.