I searched the library of the ACM - Association for Computing Machinery - at ACM.ORG and found no references to Transmemory.
Similarly at IEEE.ORG - Institute of Electrical and Electronics Engineers - there were no direct hits although there was one loose reference in an article about Transactional Memory where Trans was found near Memory.
Possibilities are:
1. Typo or misunderstanding by the tech writer of a term used by an engineer. Sometimes the knowledgeable person doesn't thoroughly proofread or fact check written documentation. There was a famously documented feature of a MS technology that was published which was quite wrong. Engineering eventually corrected the mistake after said documentation was quietly pulled they claimed they never said it and it was never written. Stuff happens.
2. Microsoft has invented a new technology for which no documentation exists (nothing in Technet or MSDN) probably because the patent is pending
although nothing shows up in a search of the USPTO database except the TradeMark filing by Toshiba for a USB stick.
3. Other, you decide.