48-bit floating point
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Norsk Data 48-bit single precision format:
| bit 47 | (1 bit) | Sign bit |
| bit 46-32 | (15 bits) | Exponent |
| bit 31-0 | (32 bits) | Mantissa |
Exponent has a bias of +256. (Subtract 256 to get true exponent)
Special values for exponent:
| All bits zero except sign bit: | Floating underflow. |
| 0 (binary 0, aka 0x00): | Zero |
Mantissa has an implicit 33th bit of 1 (unless mantissa is 0). This is the 0.5 bit, i.e. mantissa is normalised to be 0.5 < mantissa < 1.0
Decimal point is thus to the left of the implicit 33th bit.
The 48-bit floating point format is only used by the 16-bit ND computers, the 32-bit computers used the 32-bit format as its single precision format.