IBM 1620 1 Manual page 84

Appendix C (cont'dJ
Character Coding
80
CD
o
ALPHABETIC MODE
Disk storage operations can be in numeric mode only.
Two-digit character representations is shown for convience.
Dump Numerically instruction only. For Write Alphamerically and Write Numerically instructions an
EOl
character is
punched in paper tape and no output is provided on the typewriter.