Old English dyde, past tense of do (v.). The only remainder in Germanic of the old linguistic pattern of forming a past tense by reduplication of the stem of the present tense. Far back in Germanic the equivalent of did was used as a suffix to make the past tenses of other verbs, hence the English -ed suffix (Old English -de).
It's interesting that a similar thing didn't happen for the word shall or will, in order to create a future tense. For example, using a suffixe from "will", like "-ll" or "-ill" for a future tense.
According to The Online Etymology Dictionary:
It's interesting that a similar thing didn't happen for the word shall or will, in order to create a future tense. For example, using a suffixe from "will", like "-ll" or "-ill" for a future tense.