split binary files using dd

dd              count=1000000 if=input.dat of=output1.dat bs=1
dd skip=1000000 count=1000000 if=input.dat of=output2.dat bs=1
dd skip=2000000 count=1000000 if=input.dat of=output3.dat bs=1

See also

• How do I extract a single chunk of bytes from within a file?