I have not updated this blog in a couple of weeks. I have been busy at work as well as working on this project. I have pretty much finished the video section of the Apple IIE. All modes look good to the eyes. The FPGA board has switches that I am using to set the different modes.
I uncovered a timing issue with the memory access interleaving. When the FPGA utilization increased, the timing shifted. This cause much of the external memory to become unstable. After much testing and simulation, the issue was found to be in the memory writes. I have fixed this issue and now things are much more stable.
I may not be able to do much work on the project in the next couple of weeks because of my work schedule. And after that, I need to build a little bit of hardware to interface a bigger ROM. The FPGA has 12K of ROM and that is not enough for an Apple. So I am going to add some Flash. I am not sure if I will use a normal Flash chip or a Compact Flash module. This could be used under Prodos as a Hard drive.