An example of MS-DOS's command-line interface, this one showing that the current directory is the root of drive C. MS-DOS (/ËÉmÉsËdÉs/ EM-es-DOSS; acronym for Microsoft Disk Operating System) is a discontinued operating system for x86-based personal computers mostly developed by Microsoft.
Written by: Kierstan Boyd. Nov. 08, 2012. The main symptom of vitamin A deficiency is vision loss and blindness. Vision loss often begins as a problem adjusting to seeing in the dark, or night blindness. People with night blindness do not see well in the dark, but are able to see normally if enough light is present.
Symptoms of vitamin B12 deficiency. Anaemia and anaemia caused by a lack of vitamin B12 can result in symptoms which include: 1  Extreme tiredness or fatigue. 2  A lack of energy or lethargy.3  Being out of breath. 4  Feeling faint. 5  Headache. 6  Ringing in the ears (tinnitus). 7  Lack of appetite.naemia and anaemia caused by a lack of vitamin B12 can result in symptoms which include: 1  Extreme tiredness or fatigue. 2  A lack of energy or lethargy. 3  Being out of breath. 4  Feeling faint. 5  Headache. 6  Ringing in the ears (tinnitus).