Designing the Videopac SDCart. 2: The SD Cart demo
Introduction I managed to get several ROM binaries on an SD card to interface and run on the Videopac G7000. Last weekend I made a video about the progress so far. It was not all easy. The damn roms wouldn't run from the SRAM. Some problems were ironed out, but remaining was the problem of which address lines to use. The buses were isolated with three 8-bit transcievers, but two of them might be replaced by resistors. Sören Gust's gold mine recide in the archive.org. It was complete with design files for the G7000 RAM cart where you can connect a PC and transfer a ROM via serial. He also shared his source code and documents on the bios library. The Program Memory Map Often address line A10 is not used in game carts. Lets have a look at the memory map. In the program memory map for the Intel 8048, the first 1kb is reserved for the internal program memory, and the remaining 3kb is external program memory. These are accessed with A11..A0. Port1 pins P0 and P1 can be