Print_Str_yx ($F378)
This routine prints a single string (up to an 0x80), using the default height and width, as stored in $C82A. The parameter block describing the string is pointed to by the U register. The format for the parameter block is as follows:
rel y, rel x, string, 0x80
ENTRY:
DP = $D0
U-reg points to the string list
EXIT:
U-reg points to the byte after the terminating 0x80
D-reg, X-reg trashed