wˈʌn mˈuːvɪŋ hˈɛd ˈæksɛst ˈiːtʃ dˈeɪɾə sˈɜːfɪs twˈɛnti tˈoʊɾəl, wˈʌn mˈoːɹ hˈɛd wʌz dˈɛdᵻkˌeɪɾᵻd tə ðə sˈɜːvoʊ mˈɛkənˌɪzəm.
One moving head accessed each data surface (20 total), one more head was dedicated to the servo mechanism.