The OpenRISC architectural simulator, Or1ksim, is a traditional interpreting ISS, which also models some of the standard ORPSoC components (memory, UART etc). It represents work in progress. Having been dormant for two years, the project is now active again.

This section is mainly concerned with Or1ksim 0.3.0 candidate release 2 and later, since this version is the first to implement the GDB Remote Serial Protocol. This is now the recommended interface from GDB to Or1ksim. The old OpenRISC 1000 Remote JTAG Protocol is still part of the system, but is now deprecated.

Since version 0.3.0 is still regarded as a development version of the tool. This section also covers the use of the stable version 0.2.0.