Besides the other uses of dd (Section 21.6) we've covered, you also can use this versatile utility to convert:
fixed length to variable-length records (conv=unblock), and the reverse (conv=block)
uppercase to lowercase (conv=lcase), and the reverse (conv=ucase)
ASCII to EBCDIC and the reverse (conv=ebcdic, conv=ibm). If you're converting old IBM tapes, you'll need to know the tape's blocking factor. And if the tape has multiple files on it, you'll have to use the tape device name that allows "no rewind on close" (Section 38.5) to read past the first file.
The cbs= option must be used to specify a
conversion buffer size when using block and
unblock and when converting between ASCII and EBCDIC.
The specified number of characters are put into the conversion buffer. For
ascii and unblock conversion,
trailing blanks are trimmed and a newline is added to each buffer before it is
output. For ebcdic, ibm, and
block, the input is padded with blanks up to the
specified conversion buffer size.
— TOR