Tandy used the "TRS-80" name for many of their computer lines, even when they used completely different architectures.

The original TRS-80 ("Model I"), the TRS-80 Model III, and the TRS-80 Model 4 all used a Z80. https://en.wikipedia.org/wiki/TRS-80

The TRS-80 Color Computer ("CoCo") used the 6909. https://en.wikipedia.org/wiki/TRS-80_Color_Computer

The portable TRS-80 Model 100 used an 8085. https://en.wikipedia.org/wiki/TRS-80_Model_100