an impact printer of the daisywheel type mechanically links together two daisywheel printer carriages so that the total number of different characters that can be printed is doubled . suitable coordination logic provides for operation in a first concurrent mode where the user &# 39 ; s software looks ahead to provide for continuous printing along a single line . the other mode of operation is sequential where the twin print heads are substantially transparent to the user &# 39 ; s system and thus the appropriate print head automatically positions itself to a printing position .