M-TD, short for "miniaturized translator droid" and nicknamed Em Teedee, was assembled by Chewbacca and programmed by C-3PO when Chewbacca learned that his nephew, Lowbacca, was planning on attending Luke Skywalker's Jedi Praxeum.
Em Teedee schematics.
M-TD was presented to Lowbacca by his uncle Chewbacca when the young Wookiee arrived at the Jedi Praxeum. Anyone who had spent a significant time with C-3PO was struck by the uncanny resemblance of M-TD's personality to that of his programmer. M-TD annoyed Lowbacca and his friends to no end because of his tendency to embellish his translations of Lowbacca's statements. He reasoned that his translations were more refined and would make Lowbacca sound more civilized.
Lowbacca himself would cause M-TD much distress by not affixing the little droid securely enough to his syren fiber belt and accidentally letting him fall. On one of the first such occasions, the young Wookiee was ripping through the Yavin 4's jungle at a fast pace, trying to get word to the Praxeum that Jacen and Jaina had been kidnapped by Qorl, a TIE fighter pilot who had been living in the jungle since the Battle of Yavin. M-TD came to a soft landing without hitting the ground, but he was claimed as a prize by a woolamander. Fortunately for M-TD, he was found by a wayward Tenel Ka, who then used his navigational capabilities to return to the Praxeum and by extension, return him to his owner.
A view of Em Teedee from the top back.
M-TD was later kidnapped by the Shadow Academy along with Lowbacca and the Solo twins during the raid on GemDiver Station. He was immediately taken away from Lowbacca which caused a great deal of confusion between the young Wookiee and his Human friends. After Lowbacca gave into his anger, smashing a sonic generator beyond repair, M-TD was given back to him as a reward by Tamith Kai.
However, something was definitely wrong with M-TD: He had become uncharacteristically defiant of Lowbacca; He would reproach Lowbacca whenever he broke the rules of the Shadow Academy; And most worryingly, he would spout phrases such as "The Empire is your friend" and other pro-Imperial propaganda. As he had been happy to inform Lowbacca, M-TD had been reprogrammed by Brakiss and Tamith Kai to become an "integral part" of Lowbacca's instruction at the Shadow Academy.
A view of the back of Em Teedee
Due to several threats made by Jacen, Jaina, and Lowbacca, M-TD helped them escape from their prison, though. While he warned the trio that he felt he had the responsibility to sound an alarm, M-TD's programming didn't hinder him from slicing into the Shadow Academy's computers to obtain passwords that would seal all of the Shadow Academy's doors and turn off its cloaking device. This was followed by an alarm. When they were finally rescued, M-TD's old programming was restored and he was back to his old annoying self, but he remained "exceedingly vexed" toward Brakiss and Tamith Kai for causing him to violate his primary programming.
Sometime thereafter, M-TD accompanied Lowbacca and his friends on their vacation to Coruscant. Upon reaching the planet he was elated to find his programmer, C-3PO, was there to greet them. The two droids would tell each other of the harrowing experiences that had occurred to them since they had last seen each other.
Lowbacca's vacation—and by extension M-TD's—would be cut short with the discovery that the cloaked Shadow Academy had been orbiting Coruscant while abducting Coruscanti youths and causing havoc for the traffic that had been flowing in and out of Coruscant.
M-TD accompanied Lowbacca on the mission to Myrkr in 27 ABY. Lowbacca detached M-TD and left him aboard the Tachyon Flier. He was aboard the ship along with a barely conscious Raynar Thul when the Dark Jedi Lomi Plo and Welk stole it. The last that the strike team heard of him was his complaint that he was being stolen. M-TD was destroyed after the Tachyon Flier crashed on the planet Yoggoy in the Unknown Regions. His remains were discovered by Jacen Solo in 35 ABY, although he could barely recognize it, the little droid being melted and fused to the floor.
M-TD attached to Lowbacca's belt.
Capable of speaking six different languages after he was programmed, M-TD specialized in Human-Wookiee relations. M-TD's yellow photoreceptors could provide illumination to compensate for varying degrees of lighting. He also featured olfactory, directional and auditory sensors. Since Lowbacca was going to spend a large amount of time on Yavin 4, Chewbacca also installed a limited database of the jungle moon's geography and wildlife in M-TD's memory banks.
A system of Micro repulsorlifts was installed on M-TD when he accompanied Jacen, Jaina, Tenel Ka, and Raynar Thul on a mission to the factory world of Mechis III. Additionally, his language database was increased by ten, bringing the total number of languages to sixteen that M-TD could translate.
In contrast, C-3PO is able to speak more than six million languages.
Throughout the Young Jedi Knights series, where he first appeared, his name was always spelled "Em Teedee." The "M-TD" spelling was introduced into canon later.
The appearance of an M-TD unit on Coruscant immediately after the Clone Wars in Republic 80 should be regarded as an anachronistic continuity error.