User Accessible Flash Memory

i have  TC55 with 4.1.2 Android, 8 GB FLash Memory and 1 GB RAM.

TC55 Non-GMS displays Flash Memory -->   4.59 GB Internal Storage and another 1 GB internal memory as per below image , But only the 1 GB Internal memory is accessible from the computer when connected via USB.


Does this mean that 4.59 GB are not accessible for user and are available only for installed applications?

is there any way to access the full memory (8 GB)?