On some versions of SCO OpenServer a problem is seen logging into terminals where getty is flushing data after the Login: prompt.
Try adding -n to the getty entry:
From the man page:
Disables the keyboard flush delay for reliably connected serial lines. Without this option, getty discards input for a short time (about 1 second) after displaying its prompt. This is to avoid interpreting modem connect noise or a directly connected system''s login prompt as a user name. The delay is automatically disabled on console multiscreens.
Aug 08, 2017