Xtrs is an X-based emulator for the Tandy/Radio Shack line of Zilog Z80-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 Z80 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.)

xtrs is maintained upstream at GitHub: see .