Motorola 700/800-Series User Manual

Floating Point Support

4-19

4. The sign field, the exponent field, and at least the first digit of 

the mantissa field must be present (any unspecified digits in 
the mantissa field are set to zero). 

5. Each field must be separated from adjacent fields by an 

underscore. 

6. All the digit positions in the sign and exponent fields must be 

present. 

This format would appear in memory as:

A single precision number takes 4 bytes in memory. 

This format would appear in memory as:

A double precision number takes 8 bytes in memory. 

The single and double precision formats have an 
implied integer bit (always 1).

1-bit sign Þeld

(1 binary digit)

8-bit biased exponent Þeld

(2 hex digits. Bias = $7F)

23-bit fraction Þeld

(6 hex digits)

1-bit sign Þeld

(1 binary digit)

11-bit biased exponent Þeld

(3 hex digits. Bias = $3FF)

52-bit fraction Þeld

(13 hex digits)