Golden Delicious

Creating a portable Apple ][ by using the MEGA II chip from an IIgs. (This chip was also known as the Gemini in the Mac LC compatibility card.)

This project is why I started Bit Preserve, a project to archive vintage computer schematics.

(Off-)Stream Notes 2021-10-02

• Attempting to book the GD with a IIc ROM results in a lock-up.
  • graphics get initialized and the memory is dumped to the screen, but no beep and nothing past that.
  • Logic Analyzer suggests BASICINIT is doing a monitor version check in the F8 ROM, but failing. It calls a jump called HANG. Even though the 6502 should be jumping in a circle, it seems to keep doing other stuff. (Maybe it is just bus fetches that do nothing?)
• SLOTMAKER Bus Headers on the IO board are pinned out different from the SLOTMAKER Bus Header on the MEGA-65c02. For a ribbon cable, each pin-pair needs to be swapped, except for the last two. They are GND.

Stream Notes 2021-10-01

Golden Delicious Rev 2 booted! Yay!

• ~DMA is wrong level

  • The two `245 buffers have their enable pins connnected to ~DMA. I made the mistake of thinking that MEGA drove the ~DMA signal. That is not the case, nor does it make sense after thinking about it. For now, the `245s have pin 19 lifted and tied to ground to always enable them.
  • When connecting the IWM or a card to slotmaker, ~DMA situation needs to be resolved.

• IIe / 6502 decoder for Waveforms / Digitial Discovery has been updated.

• This forum post has Digilent Waveforms beta builds that are downloadable without filling out the annoying registration form. (Or just use asdf for all of the fields.)

Stream Notes 2021-06-02

• Wherefore no IIe ROM in the IIgs? Is it in the MEGA-II?
• Warphammer: this seciton looks rommy