A bit-paired keyboard is a keyboard where the layout of shifted keys corresponds to columns in the ASCII (1963) table, archetypally the Teletype Model 33 (1963) keyboard. This was later contrasted with a typewriter-paired keyboard, where the layout of shifted keys corresponds to electric typewriter layouts, notably the IBM Selectric (1961). The difference is most visible in the digits row (top row): compared with mechanical typewriters, bit-paired keyboards remove the _ character from 6 and shift the remaining &* from 7890 to 6789, while typewriter-paired keyboards replace 3 characters: ⇧ Shift+2 from " to @ ⇧ Shift+6 from _ to ^ and ⇧ Shift+8 from ' to *. An important subtlety is that ASCII was based on mechanical typewriters, but electric typewriters became popular during the same peri