In going through and sorting my piles of classic ICs,
I ran across this
Western Digital WD2793A chip. What is it?
It's a later replacement for the 1793 FDC. But not a drop-in replacement.
It has an on-board analog data separator, while the 1793 required an external
data separator.
Some of the other 179x replacements had better digital data separators.
I've personally always had good luck using the 179x with external
SMC 9216 or 9229 data separators, which are probably hard to get by now.