emulator for TRS-80 Model I/III/4/4P computers

 xtrs is an X-based emulator for the Tandy/Radio Shack line of Zilog
 Z-80-based microcomputers popular in the late 1970s and early 1980s. It
 features cassette, floppy, and hard drive emulation, timer interrupt
 emulation, file import and export from the host operating system, support for
 most of the undocumented Z-80 instructions, and a built-in debugger. Real
 floppy drives can be used, and, if an OSS-compatible sound driver is
 available, application-based sound can be played and real cassettes read and
 written directly through the sound card or via WAVE files. Several hi-res
 graphics cards are emulated and, in Model 4/4P mode, mice are supported.
 There is also real-time clock, sound card, serial port, joystick, and CPU
 clock speedup emulation.
 .
 xtrs requires ROM images from the original machines. The ROMs are
 copyrighted by Radio Shack and are not freely licensed. (Exception: in Model
 4P mode, a freely licensed boot ROM included with this package can be used to
 boot a Model 4 operating system from a diskette image.)