The Or1ksim ISS is configured using a textual configuration file, described in more detail in Embecosm Application Note 2. The OpenCores OpenRISC 1000 Simulator and Tool Chain: Installation Guide. [4]. For the modified Or1ksim ISS, generic peripherals can be added (see Section 4.1.2), which will cause code to call out via the upcall mechanism to the Or1ksim SystemC wrapper module (see Section 4.2.6).

The Or1ksim configuration file for this example is in simple.cfg. It disables all the standard peripherals and specifies one block of memory from address 0x0. It adds a generic peripheral allowing byte, half word and full word access to addresses mapped from 0x90000000 to 0x90000007, with the following configuration file entry

section generic
  enabled      =          1
  baseaddr     = 0x90000000
  size         =        0x8
  name         = "External UART"
  byte_enabled =          1
  hw_enabled   =          1
  word_enabled =          1
end