bsplit?

[Ken Yap]

|The real problem, though is that you can't feed the script from a
|pipe.  dd is almost unique among the unix tools in that it
|uses read() rather than fread() and will fail to read the
|requested amount if the input pipeline cannot stay ahead.

There is a good reason for that, the semantics of reading large blocks
from tape have to be preserved. If stdio were used, the block size
would be whatever stdio happened to use. No doubt dd could be taught to
tell the difference between tape and pipes but nobody wants to mess
with nostalgia. :-)