Tektronix 2212 - Page 171

General Product Description
If the ADD, ALT or CHOP mode is selected in Store mode, the sig-
nals applied to the vertical input connectors are acquired
similtaneously. However, if the vertical mode is in ALT and the
trigger source is in VERT MODE, CH 1 and CH 2 will be digitized
alternately.
2212 User Manual
B-3