Symmetricom X72 User Manual

097-10603-01 Rev. A – November 2004 X72 Desiger’s Reference and User’s Guide 61
Using the Symmetricom Serial Interface Protocol
Factory Mode
Data output from the X72 in factory mode is not intended for users outside the
factory and is not described in this document beyond Table B-1.
Floating Point Number Representation
The host PC must convert Floating Point numbers output by the X72 to the host’s
own floating point using the definition shown in Table B-1. Likewise, the host’s
floating point numbers must be converted to X72 coding before being sent to the
X72.
Single precision floating point format is a 32-bit format, consisting of a 1-bit sign
field, an 8 bit exponent field, and a 23-bit mantissa field. The fields are defined as
follows:
Sign <S>: 0 = positive values; 1 = negative value
Exponent <E7-E0>: offset binary format
00 = special cases (i.e. zero)
01 = exponent value + 127 = –126
FE = exponent value + 127 = +127
FF = special cases (not implemented)
Mantissa <M22-M0>: fractional magnitude format with implied 1
1.M22M21. . . M1M0
Range: –1.9999998 e+127 to –1.0000000 e–126
+1.0000000 e–126 to +1.9999998 e+127
(where e represents 2 to the power of)
Caution: Using factory mode can result in the erasure of firmware on
the X72 rendering it inoperable and making it necessary to return the
unit to the factory for re-programming.
Table B-1. Floating Point Number Representation for SSIP
Floating Point Format – Single Precision
31
S
30
E7
29
E6
28
E5
27
E4
26
E3
25
E2
24
E1
23
E0
22
M22
21
M21
20
M20
19
M19
18
M18
17
M17
16
M16
15
M15
14
M14
13
M13
12
M12
11
M11
10
M10
9
M9
8
M8
7
M7
6
M6
5
M5
4
M4
3
M3
2
M2
1
M1
0
M0

Symmetricom X72 Specifications

General

Brand	Symmetricom
Model	X72
Category	Test Equipment
Language	English