Emacs provides a method for working out numbers in two’s complement form

M-x calc Turn on calc mode O d2 Turns on two's complement binary b w 8 Sets the word length to 8 bits d z Displays leading zeroes

Now you can enter numbers. Don’t forget to use underscore for negative numbers

_3 (-3) gives 2##11111101

You can press y to yank the result back into the last buffer.

## Quick Conversions

if you want to quickly convert between binary, denary and hex you can use quick calc mode:

To convert 17 from Denary to Binary

To convert 17 from Denary to Binary

C-x * q Enter quick calc mode 17 Hit enter Result: 17 => 17 (16#11, 8#21, 2#10001, "")

To convert 1100 from Binary to Denary (or Hex)

C-x * q Enter quick calc mode 2#1100 Enter in minibuffer. Use 16# to enter a Hex number Result: 12 => 12 (16#C, 8#14, 2#1100, "")