²The original flight software design called for bias map packets to be interleaved, i.e., trickled with event telemetry at the start of each science run. However, a firmware error caused FEPs to latch-up if the number of event candidates exceeded a limit that was often reached, especially when processing data from front-illuminated CCDs. The flight software was therefore rewritten prior to launch to run the BiasThief task to completion before starting the ScienceManager task. Once in orbit, it was discovered that the change didn’t always work – in a few instances, the two tasks ran simultaneously. This was finally prevented by the busCrash2 patch installed in 2010 (see Appendix F).