All editions of the TR represent the true Greek text of the Bible as found in the bulk of manuscripts, translations, lectionaries, and the writings of the Early Church Fathers.
After Erasmus produced the first printed Greek text of the New Testament in 1516, other textual scholars worked on it for about 100 years. During that time there were only minor revisions to the text. Eventually the Greek text of Stephanus from 1550 became what is now known as the Textus Receptus. But the Elzevier brothers continued to work on it into the 17th century (again with only minor variations).
At the same time there were minor variations from the text of Stephanus which were incorporated into the KJB (since those translators had access to all the editions of the TR since Erasmus). So F.H.A. Scrivener -- the leading textual scholar of the 19th century -- produced the actual KJB Greek text in 1894 (with added punctuations). But it is almost identical if not 100% identical to that of Stephanus. Here is an example from John 1:1:
Scrivener's Textus Receptus 1894
Ἐν ἀρχῇ ἦν ὁ λόγος, καὶ ὁ λόγος ἦν πρὸς τὸν Θεόν, καὶ Θεὸς ἦν ὁ λόγος.
Stephanus Textus Receptus 1550
Ἐν ἀρχῇ ἦν ὁ λόγος καὶ ὁ λόγος ἦν πρὸς τὸν θεόν καὶ θεὸς ἦν ὁ λόγος
As you can see, Scrivener simply added punctuations in this verse. So for all practical purposes, the TR has remained the same.