Commander X16

Are there any tutorial for creating a ROM cartridge from start to finish step by step? If you mean the hardware part, I've got a 'tutorial' schematic at https://github.com/jkominek/x16simplecart which includes gerber files for a PCB you can have made for personal use. Or you can work through the sc...

Hrm, wrote another reply which I probably failed to hit 'submit' on. I hooked up my serial card (which, again, is not the TexElec card, but one of my own design using an original 16550, which does not support auto RTS/CTS) to a Linux system via null modem cable. I then had a small program send a scr...

Hm, so, all of the lines are being measured physically on my serial card, except for PHI2 and VPB. VPB is generated in the CPU, after it sees IRQB go low, and variations will be dominated by what instruction is being executed when the IRQ hits. Since PHI2 is being measured at the CPU, and everything...

There were some concerns a few weeks back with at least one person convinced that the serial card's UART had a "slow" interrupt. I finally got around to taking measurements, so I'm presenting them here to lay that to rest, and explain what the actual issues are. Here's a logic analyzer cap...

I've mentioned this stuff on Discord, but to spread it around further: I've put together a KiCad library for expansion cards and cartridges. It includes two different symbols, and then two different footprints. One for cards, and another for carts that has been tested to fit in aftermarket Famicom c...

I wrote a long post and then the stupid forum decided I needed to log in again, and lost it. Not typing that again, sorry. I think desertfish has the right idea. You need to eliminate all of the calls to tile_exists, by arranging for the code that accesses the board to never want to access a tile th...