So they did, but DEC machines in general were always ASCII.  The PDP-8
used both 8-bit characters (ASCII with the high bit set) and 6-bit
ones (stripped ASCII without control characters or lower-case ones).
The former were packed three 8-bit characters in two 12-bit words; the
latter, two characters in one 12-bit word.  The PDP-10 packed five 7-bit
characters into a 36-bit word with one bit left over, which was used
(if at all) for various purposes.  Not until the PDP-11 did the 8-bit
character get aligned with the machine word size.