0F 1F /0 is documented as an EA-taking NOP since the P6.
0F 18..1F + EA are all "hinting nops" (instructions which, when
unimplemented, have no effect rather than #UD) but 0F 1F /0
specifically has no operation whatsoever.
NEG rm32 \321\300\1\xF7\203 386
NEG rm64 \324\300\1\xF7\203 X64
NOP void \1\x90 8086
+NOP rm16 \320\300\2\x0F\x1F\200 P6
+NOP rm32 \321\300\2\x0F\x1F\200 P6
+NOP rm64 \324\300\2\x0F\x1F\200 X64
NOT rm8 \300\1\xF6\202 8086
NOT rm16 \320\300\1\xF7\202 8086
NOT rm32 \321\300\1\xF7\202 386