Frodo, Frodo PC and Frodo SC

Frodo comes in three 'flavours' that allow you to decide between speed and accuracy of the emulation.

The line-based emulation 'Frodo'

Frodo is a line-based emulation, i.e. the activities that happen in parallel during one video line in the real C64 are emulated one after the other for the different chips. This offers a reasonable degree of precision of the emulation at a decent speed. There are some things that cannot be emulated with this technique, but it works fine with about 80% of all C64 programs and it is also the fastest of the three Frodo versions.

The improved line-based emulation 'Frodo PC'

Frodo PC is also a line-based emulation but it has some improvements over the standard Frodo: Programs that don't work on the standard Frodo or that produce an "Illegal jump to I/O space" message might work with Frodo PC. However, Frodo PC is a bit slower.

The single-cycle emulation 'Frodo SC'

Frodo SC is a special version of Frodo that doesn't work with a line-based emulation but instead with a cycle-based one. That means that the emulator switches between 6510 and VIC in every emulated 2 clock phase. By doing this, Frodo SC achieves an extreme precision (nearly all $d011 and $d016 effects can be emulated), but at the expense of speed. In the settings options, Frodo SC differs from Frodo/Frodo PC in only a few points: Apart from that, Frodo SC is operated in the same way as Frodo and also uses the same settings. Frodo SC has only a few incompatibilities to a real C64: