Simulation of transactions

A non-transitory storage medium storing a computer program comprising:

• simulation program logic to perform, in a series of time periods, simulation processing on a host data processing apparatus to simulate operation of a plurality of simulated agents of a target data processing apparatus processing target program code, in which during each of the time periods, the simulation processing exclusively simulates operation of a single simulated agent of said plurality of simulated agents;
• the simulation program logic comprising transaction simulation program logic to simulate processing of a transaction comprising one or more instructions executed between thea transaction start instruction and a transaction end instruction for which effects of the instructions of the transaction are to be committed when the transaction end instruction is reached in the absence of the transaction being aborted;
• in which:
• when the target program code processed in a current time period allocated for simulation of a given simulated agent includes a transaction start instruction representing a start of a transaction, the transaction simulation program logic is configured to:
• detect whether an end of the current time period occurs before the transaction end instruction of the transaction is reached;
• and
• abort the transaction when it is detected that the end of the current time period occurs before the transaction end instruction of the transaction is reached.