Indeed, the assumption is that, as the FDC is controlled by DFS, once it has gone idle it won't wake up again unless DFS programs it to do something. With Econet, there can be activity on the network whether or not any individual station is trying to use the network so that is, perhaps, why the Econet hardware has a feature to stop the interrupt request form the ADLC asserting the NMI line.The 1770 command set documentation states all commands complete with an interupt. The BBC uses a shared NMI system, so when a filing system releases its claim on the NMIs it needs to disable the interupts from its hardware. However, I can't see anything in the Master hardware that disconnects the NMI line in a similar way to the Econet hardware. I think the disk firmware relinqished NMIs by just telling the hardware to go idle and assumes it won't generate any interupts until it is next accessed.
Statistics: Posted by Coeus — Sun Sep 01, 2024 7:26 pm