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Hi65 is a high-level Commodore 65 emulator.

In order to understand what "high-level" means, let's first consider what a "low-level" emulator does. It implements a software version of the whole machine, including a virtual processor that executes machine language commands.

When any software for the target platform is loaded into the virtual RAM, the virtual processor executes it instruction by instruction.

However, the Commodore 65 is not the ideal platform for a low-level approach: each of the few units around has a different implementation of its ROM software, the implementations themselves are buggy and there is no commercial software around. The authors of MESS want to emulate the Commodore 65 with a low-level approach, but that has been a failure: the C65 driver of MESS has had the same bugs for over a decade, bugs that do *not* appear in the actual C65 prototypes. Emulating the Commodore 65 with a low-level approach is not "accurate" and it's more than pedantic: it's a self-defeating task.

Enter Hi65.

Hi65 does not implement a virtual version of the 4510 CPU (used in the physical Commodore 65), nor does it execute machine code software: it executes tokenized BASIC 10 programs directly, as if the various BASIC tokens were machine code instructions for its own virtual processor. Thus, the execution is much faster because it's not limited to the clock speed of the 4510 (but the timing is still accurate) and it's not limited by the scarce knowledge of the inner workings of the Commodore 65, because all instructions are made to do what the manual says they should do, not what they actually do on a physical machine (which may be buggy and inconsistent between individual machines).

The high-level approach makes Hi65 much faster than MESS, and even faster than the original machine. The gfxdemo1 program is completed correctly in a tenth of a second in Hi65. The same program takes 4 minutes and 44 seconds to be completed on MESS 0.106 with throttle off. This means that the high-level approach chosen with Hi65 makes it 2840 times faster than MESS. The same program is completed in about 20 minutes on a physical Commodore 65, which means Hi65 is 12000 times faster than a physical Commodore 65.

Hi65 (the emulator), Hi65CFG (the configuration software) and Hi65 Launch Tool (the graphical frontend) are released under version 3 of the GPL (GNU General Public License). If you do not have a copy of the license, go to http://www.gnu.org/licenses/gpl.html to read it.


Hi65: a high-level Commodore 65 emulator