The Tektronix M163 (P/N 155-0026-00) is a character generator (S V A W H d B c Ω E) monolithic integrated circuit in a 16-pin plastic DIP, designed by Barrie Gilbert for the 7000 series readout system.
It is an analog read-only memory used as a Character Generator for code row 5, 10 letters (S V A W H d B c Ω E).
The letter "S" is in upper case, therefore the 7000 series somewhat incorrectly display time units, e.g. "mS" would actually indicate milli-Siemens (aka "mmhos", unit of conductivity) instead of milliseconds.
The 155-0023-00 through 155-0027-00 (M160-M164) share the same silicon and differ only in the metallization layers.