What is the memory map of a w65c02s?
What is the memory map of 65c02w?

Well, &quot;vestigial&quot; would be a misnomer, because that implies that it had one to begin with.  &quot;Mostly up to you&quot; would be a better way to put it.

The datasheet is not clear at all compared to the atmega328p.

From the perspective of a modern microcontroller like the atmega328p, a first-generation microprocessor like the 6502 is just a core.  There's a bit of memory that must be populated (see Brian Drummand's comment), there's a few fixed locations for interrupt and reset vectors -- and that's it.  It's up to the board designer to provide I/O, make sure there's flash that covers those vectors at $FFxx and RAM at $0000-$001FF.  Beyond that -- whatever you design in, that's what you get.
Most of the early microprocessors were designed to have RAM at one end of the memory space and ROM at the other -- this one would have been RAM at $0000 up, and ROM at $FFFF down.  If they didn't provide a specific I/O bus like the Z-80 (and, I think, the 8080) then you'd use memory-mapped I/O in the middle.
But it was very much up to you -- a &quot;microcontroller&quot; like the current crop of AT-Mega chips would be realized by a board six inches on a side, but with the peripherals hard-wired and with many fewer of them.