martyn_hill wrote:BTW - given recent experience re-working the QNET driver around Q68's hardware-timer, I can say that any 8302 replacement should have a high precision timer included - it would make any further QNET driver development soooo much easier...
A high-precision timer is also helpful for other tasks, where the 50 Hz timer does not provide sufficient granularity. (And sorry for not yet finding time to update the Q68 manual). I'd recommend it for a future hardware like a 8302 replacement, or a new CPU board, too.
However, while the timing measurements are very accurate, code execution from SDRAM on the Q68 can be delayed during video access by several microseconds. (This is because video data is transferred in bursts to increase performance.) So unfortunately, the QLNET implementation on the Q68 was not as straightforward as it seems. Some code and data needed to be moved to SRAM.