glb_gtz's blog

Moving to the end

Now that I have the boot issue fixed, I am working on the floppy. I have it mostly working. I am able to use FILER to format the two drives. I am also able to store data on the drives. I can run programs from them. I can even use Copy II Plus bit copy and copy one disk to the other. But a few things still are not right. The first issue is booting from the drive. I can do a PR#6 and it will go to track 0, then it moves the head to track 1. I assume it read the boot blocks and is looking for PRODOS. I am having an issue with Copy II Plus also.

Smoking Gun for sure

Finally the debug effort is finished. I traced the no boot issue to a bug in ProDOS. This error exists in both ProDOS version 1.2 and 1.9. But I see it has been fixed in version 2.0.1. I just need to do a work around in my ROM code to make sure I do not trigger this bug. Then I can continue firmware development of the Serial Virtual Drive. When I get this working, the floppy is the next task. I have done some testing on the floppy and I believe it is working. But the final test will be to load a DOS 3.3 image into the RAM and try to boot from the floppy.

Pictures Available

I have uploaded a couple of pictures. Look at my image gallery.

http://www.applefritter.com/image/uid/12920

These are not great quality, I took them with a camera phone. I wanted to show the status of the project. Not much has changed. As long as I have only the one drive, everything works correctly. But when I add a second drive, either floppy or serial drive, ProDOS fails to boot. I am again tracing ProDOS boot sequences to see where it fails. I do not know what else to do.

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