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.

Screenshot_1970-01-09-07-13-34.png

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)?