Testing my new seek logic for the Virtual 2315 Cartridge Facility - part 6

NEW APPROACH FOR SHADOWING SEEK IN REAL MODE

I made changes to the logic for the FPGA in the Virtual 2315 Cartridge Facility (V2315CF) to handle the glitches I saw on +Access Ready as it was passed to the 1130 disk controller logic. That feedback signal generated by the disk drive had glitches which looked like spurious changes of state to the disk controller, resulting in failure to drive the disk arm to the intended cylinder in all cases. 

For virtual mode, where the disk drive is not involved at all, V2315CF generates +Access Ready using a timer to match the specification for what the 2310 internal disk drive would do if it were hooked up natively. When an -Access Go from the 1130 requests a movement, the disk waits 5 milliseconds, then drops +Access Ready for a further duration of 10 ms. At the time that it first drops the feedback signal, the logic records how the cylinder number (disk arm position) would have changed based on the step size and direction that accompanied the -Access Go falling edge. 

I now generate the same +Access Ready signal in real mode (where the disk drive is running and performing the seeks being requested) as we do in virtual mode. Thus, we don't care about +Access Ready coming from the disk drive, we just assume that it is performing the seek as requested. This ensures that the V2315CF will interact properly with the disk controller logic and that we record every arm movement that was requested by the 1130.