I don't want to dive into the discussion about definition of terms (although I agree it is important & that the discussion has prompted a robust argument in favor of the milestone), but I do want to suggest some re-wording of the citation:
Engineers developing the Toshiba T1100, an IBM PC compatible laptop computer that shipped in 1985, pioneered the idea that computers could be used anywhere, at anytime and by anyone. With the T1100, Toshiba demonstrated and promoted the emergence and importance of true portability for PCs running packaged software, with the result that T1100 won acceptance not only among PC experts but by the business community.
My rewrite was prompted by trying to eliminate the empty phrase of "made an invaluable contribution". Instead of saying that it made a contribution, I wanted to know what that contribution was. In reading over the discussion, it seemed that a key contribution was pioneering a new environment for how users should interact with their computers. Please advise if I did not pull out the most important contribution.
My second change was prompted by wondering who was the subject who did the pioneering work. Was it the specific computer model, the Toshiba T1100, as implied by the initital wording of the citation? Was it the company, as implied by the second sentence of the citation? I propose shifting the action to the engineers themseleves, if they are in fact worthy of the credit.