glb_gtz's blog

It's all over excpt the crying

Crying .... Testing

To me about the same. I have been unable to boot the Apple ][ E ROM. But today I finally found the smoking gun, so I believe it will boot the new ROM set tonight. I have a 1000 KB ProDOS image on the ROM and the slot ROM code is being loaded also. With a little luck, it will boot completely up into ProDOS. I also have the floppy slot ROM loaded so I might be able to start testing the floppy emulation. That is the next big hurdle.

Getting closer

I have fixed most of the video issues and can reliably boot into Apple ][ mode. I was planning on posting some pictures, but I got side tracked. I finished the 128K memory code and also finished the Floppy disk emulation. I say finished, but it really is not finished until it is tested. I have done almost no testing on any of these new features. The memory I can test using an assembly language program. I am working on it now. When the memory code has been tested and debugged, I need to switch over to the Apple IIe ROMS. This will give the 80 character display capabilities.

It is alive

Well...mostly. Yesterday it looked like it was trying to boot. I was getting a ] at the bottom of the screen when I hit the RESET button. But the screen would not clear and the keyboard was not working. I should have cycled power and I would have gotten the screen to clear. Something about cold booting and warm booting. Today I fixed the keyboard, except for the space bar. And now I can run BASIC programs. I have not done much testing, but I have some issues that I need to fix. Of course, I need to fix the space bar. Also, the character K is replaced with G.

Close but no cigar

Even a near miss is still a miss. I have not gotten the system to boot. I have all the Apple ][+ memory map finished. I also added some of the 2e stuff. I am having problems with the LPC ROM, of course. Debug is going slowly. In the process of looking at the memory map, I noticed a few things that I had forgotten. My original plan was to use RAM for all the ROMs. When I was looking at some of the aspects of the Language Card, I noticed the 4k block that needed to be relocated from C000 to D000. It is weird that I do not remember that feature from my old Apple hardware.

How slow is too slow?

In my debug of the Verilog 6502, I noticed that the code was not cycle accurate with the NMOS 6502. A lot of common instructions take an extra cycle. The means that most of the time it will be running 25% - 33% slower. For me, that is unacceptable. I have been playing with writing a cycle accurate version. It is doable, but it will take a lot longer. So I am going to put that on the back burner in favor of getting the APPLE to boot. I will have to make sure I use just the 6502 ROMs.

Up and running

I have officially moved into my new abode. I set up the development board and started testing the newest code. Since I had been unable to test the ROM, I have been working on the verilog version of the CPU. Under simulation, it appeared to work. But simulation only executed about a dozen or two instructions. When I programmed the development board, it failed. It seems to be failing in a loop that uses Y as an index register into a string of character and prints it on the screen.

Where am I?

Well, forget everything I stated before. I seem to be changing my mind fairly regularity these days. I do not know if is because of the lack of sleep or I am being slowly changed by my wife to be more like her. If I was in marketing I would say, I have adapted in an everchanging environment as new information became known to me. Or some BS like that.


Prototyping the extra Flash ROM has turned out to be harder than I thought. I have decided touse a 8 Mb / 1 MB LPC bus Flash part. Since it uses the LPC bus, there is not a lot of signals to hook up. I tried to find a socket for the chip locally, but no one had one. I will need to order it from Digikey. But for the first prototype, I will just wire it up. This will allow me to get the code debugged. I have added the code to the FPGA, but without the circuit I cannot test it. I was hopeing that I would get some time over the holiday to build the circuit.

Apple - ROMs

I have most of the software switches added to the code to make the system look like an Apple 2. The next task is to add ROM to the system. This ROM is needed for the Monitor, BASIC interpreter, and to hold floppy images while I write and test the floppy emulator. I was looking at Compact Flash devices that can be used under Prodos. The issue with these is the amount of prototyping needed to make them work. I was hopeing for far less signals. I looked at multimedia flash cards (MMC) also. They have less connections and this is probably what I will end up using.

Video done

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.


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