ZXSpectr

It’s a ZX Spectrum emulator written entirely in Assembler. It runs under MS-DOS, and pretty well also in Windows and MS-DOS emulators, like Dosemu and Dosbox. It’s the first emulating the Inves Spectrum + (a Spanish clone)

You can try a newer and better emulator, made also by me, for Unix systems (Linux, Mac, Raspberry Pi and others) and Windows here:

http://sourceforge.net/projects/zesarux/

The SourceForge Speed Test measures Latency/Ping, Jitter, Download Speed, Upload Speed, Buffer Bloat, and Packet Loss. Upon completion, you can view detailed reports about your connection. This HTML5 speed test does not require Flash or Java, and works on all devices including tablets and smartphones. Host on your own infrastructure or use ours. For licensing, inquire today.