The range greatly exceeds what is needed to describe all known physical limitations within the observable universe or precisions better than planck units.
The octuple-precision binary floating-point exponent is encoded using an offset binary representation, with the zero offset being 262143; also known as exponent bias in the IEEE 754 standard.
The minimum strictly positive (subnormal) value is 2−262378 ≈ 10−78984 and has a precision of only one bit.
By default, 1/3 rounds down like double precision, because of the odd number of bits in the significand.
Apple Inc. had an implementation of addition, subtraction and multiplication of octuple-precision numbers with a 224-bit two's complement significand and a 32-bit exponent.