HP 1630A Operating And Programming Manual page 114

Model 1630A/D/G
Using HP-IB or HP-IL Interface
Real Data (R) Format
Data that is structured using the floating point system is indicated with the abbreviation (R) in the contents
column of the learn string . The floating point format used in the learn strings consists of 32 bits as shown in the
following arrangement .
BYTE 0 BYTE 1
BYTE 2 BYTE 3
EEEEEEES . MMMMMMMM
MMMMMMMM MMMMMMMM
Where:
EEEEEEE = 7-bit 2's Complement Power of 2
S = Sign of Mantissa (O=Positive, 1=Negative)
M . . .. . M = 24-bit Unsigned Mantissa (Fraction)
NOTE
When acquisition is timing trace, this number refers to number of marks or
number of sample period intervals .
The floating point format is an efficient method of representing large numbers using minimum memory space.
The interpretation of a particular parameter using real format is dependent on the context of the parameter . A
real number for a parameter involving "time" must be multiplied by a standard time increment which is peculiar
to that learn string . An example is in the Timing Trace learn string where the real numbers obtained must be
multiplied by the sample period to obtain the proper time. However, in the State Time Interval Overview Learn
String, the number obtained is always in seconds which is essentially the same as multiplying by one .
In a case where a parameter does not involve time, the decoded real number is directly translatable . This is
evident in the Timing Trace Learn String parameter for the number of marks or runs .
The following example is from a State Time Interval Learn String . A run was made which acquired a total of 76
samples in 145 .5 jsec .
The first byte (byte 14) is the exponent and is decoded as:
indicates positive number
indicates binary power of 27
The least significant bit in binary representation of the byte indicates the number is positive. The remaining
seven bits are then considered a separate binary number which, in this case equals seven . There are two ways
to interpret remainder of the number (bytes 15 through 17) .
Hexadecimal :
0 E
Binary:
0000 1110
0000
0111
(EXPONENT):
0 7
Parameter :
Total Number of States
Byte Position : 14 15
16 17
Format:
(R) (R) (R) (R)
Hexadecimal : 0 E
98 00 00