Commodore PET User Manual page 396

ASCIC$)
AND 63
again provides the numerical equivalent of C$.
631O=3F16. This AND operation zeroes the two high-
order bits of the ASCII code (which were developed in
the previous expresson), leaving the five low-order bits
ready to be ORed in. After this operation. this term has a
value of:
00XXXXXX2
where x=O or 1.
Now the OR operation is performed. producing the screen memory code
equivalent to the ASCII code of the character C$. After the OR operation .the com-
bined term has a value of:
01 xxxxxx2 or 00xxxxxx2
This is the value POKEd into the last screen position at line 150. Since no further
messages are to be printed. line 160 branches past the HIT A KEY message.
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