A computer system includes a processing unit that processes data in response to instructions read from memory. Before being ready for a user to make use of a loaded application, the system initially loads executable instructions from permanent storage (such as a magnetic disc drive) during a loading process. In order to make better use of this time, operation related data (that is data for assisting a user to operate the system) is displayed during the loading process. The operation related data is stored in a user accessible file. Furthermore, the application itself facilitates the user re-configuration of the user accessible file under the control of the processing unit when the processing unit is executing the instructions; it not being necessary to use a third party text editor and navigate through the file structure. Then, during a subsequent instruction loading process, the user re-configured data is read.