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A project log for Dragon like 6809 Retro Computer

Project to re-create a Dragon 32/64 Computer

Matt CallowMatt Callow 06/04/2021 at 23:150 Comments

I now have a working keyboard. I took an old cherry portable keyboard, which has mechanical keys and re-wired it to the dragon matrix. Wired to the keyboard PIA and it works!

Once I got the keyboard working, I was able to type in some basic programs and check out a few things. Initially I did not have the mode select pins for the VDG connected so was unable to change video modes. One odd thing I noticed was that I only has 16K of RAM reported. I suspected that this was to do with the RAM settings in the SAM. Looking at the ROM disassembly, I saw that it checks bit 2 from one of the PIAs to determine memory config. I wired this up, but it still did not work. Probably because it was now selected 32/64K dynamic RAM. I need 64K static RAM setting.

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