QDOS-tan personfies QDOS, which was developed and marketed by Seattle Computer Products for its Intel 8086-based computer kit. Initially known as QDOS (Quick and Dirty Operating System) the name was changed to 86-DOS once SCP started licensing the operating system. Her mother is DR-DOS-tan, owing to the fact that its command structure and application programming interface that imitated that of Digital Research's CP/M operating system. QDOS was later purchased by Microsoft and developed further as PC-DOS and MS-DOS.
QDOS-tan is represented as a very small and young girl (appearing to be about 5 years of age and 92 cm [3 ft.] tall) with short green hair decorated by a small wrench bearing a stylized QDOS and with pigtails held in place by large metal nuts. Her glasses function as goggles and she designed them herself. Her outfit is a schoolgirl-style outfit with a white shirt, green vest and black skirt. While she seems rough she is in fact very pleasant and charming.
She is dimwitted except in the field of mechanics in which she is a miracle mechanic able to repair any broken thing imaginable, though the more complicated the hardware, the patchier the repairs are going to be (referencing the quick and dirty nature of QDOS).
QDOS-tan had always been an immature and incomplete OS-tan. When she was very young, she was adopted by the early Microsoft Family (back when it was only Xenix-tan and the occasional visit by Altair-tan) and lived there long enough to have two additional sisters ( MS-DOS-tan and PC-DOS-tan) cloned from her genes but after their creation, QDOS-tan was soon abandoned to fend for herself. She also did not have any support from DR-DOS-tan who at the time scorned her daughters and wanted nothing to do.
Because of her lack of support during her childhood, QDOS-tan became physically and mentally stunted, with cognitive abilities limited to those of a small child. However she survived in a junkyard and grew up to be a miracle mechanic and despite the years of negligence, she is mentally incapable of feeling hatred. She adores her relatives and has been happy ever since being reunited with them. She lives with her relatives and is affiliated with the DOSSE.