Testing my new seek logic for the Virtual 2315 Cartridge Facility - part 1

PROGRAMMED THE INITIALIZATION MEMORY FOR THE FPGA

Once I had the license in hand for IceCube2 I could synthesize and generate the bitstream for the FPGA device used in the Virtual 2315 Cartridge Facility (V2315CF) main unit. I grabbed the Lattice HA-USBN-2A programming cable and plugged it into the V2315CF, then powered up the V2315CF. fired up the Diamond application and used it to update the FPGA to use my latest logic.

PRIOR PROBLEM WAS HAVING THE V2315CF AND 1130 DISK DRIVE GET OUT OF SYNC

The V2315CF should be shadowing the seek operation as the IBM 1130 system disk controller commands the internal 13SD disk drive to move the arm to various cylinders. After a sequence of moves, the cylinder where the disk arm stopped was sometimes slightly different from the cylinder that the V2315CF believed we had reached. We fed data from the wrong cylinder of the virtual 2315 cartridge, which the diagnostic program flagged as a failure to seek properly. 

My new logic should be more robust and hopefully track the seeks exactly The goal is to have the seek test of the IBM disk diagnostic pass with no errors. All the other functions such as reading and writing were proven to work correctly, thus this is the last issue before the V2315CF has passed its testing.

RUNNING THE DISK DIAGNOSTIC AGAINST THE V2315CF

I set up the V2315CF for real mode, which is where it moves the internal disk drive arm and determines its sector position based on the disk drive generated signals, but feeds data from the cartridge image we loaded into the V2315CF rather than the read/write heads of the 13SD disk drive. I inserted a virtual cartridge into the box, put a real 2315 cartridge into the 13SD drive, and powered up the system. 

I loaded the virtual cartridge image and let the disk drive spin up and become ready. File Ready light turned on at the 1130 console, indicating it was ready to be accessed. I used the memory loader function I added to the IBM 1130 to load the 1130 memory with the disk diagnostic program, then started its execution. 

RESULTS OF SEEK TESTING

The diagnostic reported that this was not a special CE test cartridge - however the same image runs properly on the 1130 simulator. This may be a problem with how I am starting the diagnostic or it could represent some issue in the V2315CF. I brought the virtual disk image home to check it on the simulator and found that it was good. That means I have some debugging to do on the machine.

One possibility is that my seek routine is not working properly yet, since the indication that we have a special cartridge is a particular word pattern 0xCEDC that is read from cylinder 199, head 1, sector 2. If I am not correctly positioned to that cylinder, the data being read would not contain that magic pattern.