The exponent is 8-bit and is stored in byte 4. It is stored with a bias of 128.
#*128-255 are positive exponents, #*1-127 are negative exponents.#*0 means, the number is zero
To obtain the signed exponent, you must subtract 128 from the stored exponent. The minimum exponent is 1 and this describes a number of 2^-127. The maximum exponent is 255 and this describes a number of 2^127.