Coloured Line

Jasper - ZX Spectrum Emulator

by Adam Davidson & Andrew Pollard

Coloured Line

Sorry, this browser is not Java(tm) enabled.

It either cannot run Java(tm) applets, or the running of applets is currently disabled in your browser.

BASIC (Online Manuals)

EDIT               F1
CAPS LOCK          F2
LEFT               F5,SHIFT+LEFT
DOWN               F6,SHIFT+DOWN
UP                 F7,SHIFT+UP
RIGHT              F8,SHIFT+RIGHT

E MODE             TAB


To run games locally place the Z80 or SNA snapshot in the same directory as the class files are in. Games are downloadable from They usually come in a .zip file which you will have to unzip that first, leaving just a single .z80 or .sna file. The full URL of the .zip file containing the Jetpac snapshot is Then click in the center of the applet and press the ESC key which will make a text field appear. Put the name of the snapshot at the end of this text field, replacing Basic.html, and press return.

If you click on the progress bar at the foot of the screen, it will speed up the emulator although on some systems you may find that this locks up your browser. If it works, subsequent clicks on the progress bar will toggle between Fast and Slow modes. In Fast mode the Spectrum will try to consume as much CPU time as it can, making the Spectrum run as fast as possible. In Slow mode if the Spectrum is running over 100% (faster than the original Spectrum) it will try to slow itself down to be closer to 100%.

The source code is available online from The AMDProgressBar class was written by Adam Doppelt.

Coloured Line