Description:
------------
a) packing the value 928 (0x3A0) and 927 (0x39F) as unsigned long ("N") always converts to 927 (0x39F)
 
b) masking the lower 8 bits of 0x3A0 always reads as 0x3F or 159

Note: phpinfo reports PHP Version 5.2.13

Test script:
---------------
$value = 928;
pack("N",$value) is 0x39f (927)

$value = 927;
pack("N",$value) is 0x39f (927)

$value = 928;
$v0 = $value & 0xff;
$v0 prints as 927

Expected result:
----------------
928 packs as 928.

Actual result:
--------------
928 packs as 927

Not good for computer to lose bits.