glb_gtz's blog

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.


I have sucessfully emulated the Apple IIE text mode and I have coded the GR and HGR. This was the easy part. I am pretty sure Woz did not design the DHGR mode. I believe the Devil had a big hand in it's development. What I wanted to do was add a monochrome mode where I could get 560x192 mode to emulate a monochrome monitor. I also wanted close to the true individual dot color. On the Apple IIE emulator, when you write a 85 into location 8192, it displays differently depending on which monitor you setup. On a monochrome monitor, it appears as 4 monochrome dots. But on a color monitor, it appers as a solid gray line. This conforms to the way it is displayed on a composite monitor. Also, it conforms to Tech Note #3. But this tech note was written before high resolution VGA monitors were on everyones desk.


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