Trash80 by Benoit
Gilon emulates an old TRS80. The emulator can only do simple text graphics,
but comes with the OS and BASIC ROM needed to run it. The version
of BASIC is as far as I can see fairly similar to the BBC BASIC many
Acorn users know and love. The TRS80 had very little hardware other than
its Z80 CPU, so is fairly simple to emulate in comparison with many other
systems.
Unfortunately development of this emulator ceased back in 1992, but the full C source code is provided for anyone else to have a play with if they're interested.
Trash80 (58Kb
ZIP file)
Benoit
Gilon's Homepage (in French)
Speed Rating:
ARM3 
There is a more advanced TRS80 driver as part of the MESS emulator. It can handle graphics as well as text and so is much more capable than Trash80, even if a bit slower. It is however one of the few MESS drivers to run at a decent speed, and in the screenshot you can see an asteroids clone running at 159% of normal speed on a StrongARM. The emulator should run most of the programs for the TRS80, and even emulates a WD 179x floppy disc controller with up to four virtual floppy disc drives contained in image files.
There is also a simulator of the TRS 80 BASIC interpreter, written in java.
Technical Information
CPU - Zilog Z80A running at 1.77 Mhz
Display- 128x48 pixels, in black and white only
Sound - 1 channel
RAM - 16 Kb upto 64 Kb
ROM - 4 Kb OS ROM
reference - Michael Koenig
Troy's
Computer Museum page about the TRS80
TRS80
tech info
TRS80
FAQ
Software:
TRS80
Games index
TRS80
software page
TRS80 support
site
TRS80
stuff
trs-80.com