I had some down time today before having to move the camper to a new site, so I ordered the cartridge hardware. I ordered two Adafruit perma-proto HATs with EEPROM, and a 6 pack of Adafruit 8 pin SOIC adapter boards from Digikey. I went with Digikey as Adafruit was out of stock on the HATs. I also hate that I can't seem to find the filter options on their site to not show stuff that's discontinued and/or out of stock. That irritates me to no end. No such trouble with Digikey. That order, to make 2 cart prototypes was $25. Pretty expensive per board, but having custom boards manufactured should bring down there board price significantly. 

The other order I placed was from LCSC in China. They're the company that makes the SD flash chips that solder right to the board. This is the main chip for these carts. I don't like that the are rather expensive though. Over $3 USD for a 1GB chip, over $11 USD for an 8GB chip. I ordered a 1GB and an 8GB card to start with. Both extremes to see what I can do with both. I may add smaller SPI flash chips such as 64Mb models in addition to the large flash chips to allow for a more permanent storage, like a ROM chip in older cartridges. I could do super cheap SD cards and sockets, but they're far less permanent and reliable. They do offer bulk discounts, so I'll see what the largest order I can afford will be after the design is finalized. Even if I never sell any, I'll just give them away to people who might be interested. Another thought was to offer a version of the board that is just a HAT with EEPROM with a micro SD card slot ties to the SDIO pins. This would just add mass storage options to a HAT which would be good for data logging and such. That might already exist, so I'll have to look into it. For that one I'd just add a big prototyping area and the SD card slot. 

The next piece of hardware is the HDMI to USB capture card since I don't own any kind of monitor or tv for use with the Pi. I already ordered that and it should be here in a few days. Will allow me to use my laptop as a monitor and pack the Pi 400 into my laptop bag. Not ideal, but will work. 

The last piece of the hardware puzzle is the Pi 400 kit. I've got plans to drive to Microcenter in a week or so to go pick one up in person and take my friend for his first adventure there. Once I have all the hardware, I'll assemble the first board and start writing code. This is a huge project for me and will be documented for others and for my portfolio. I don't know of anyone else making a new cartridge format for any modern systems, so I wanted to do it myself and see what happens. Today's orders put me one big step closer to my end goal. 

I've already got two people interested in developing games for the format. Both are artists. One amateur, one professional. Both are very talented and fun to work with. I'll be creating all of the tools needed for them to make their games a reality, or at least packaging the tools and making them easy to use and learn. Once that is done, I should have a cart dedicated to developing games for the system, with built in storage and special hardware such as real time clock modules, lights, displays, and sensors. I've got to decide on a display and lights for the upcoming pinball cart, so I took a close look at the various pinball machines I was playing last night at the arcade. I think an RGB matrix will be good, as long as the resolution is high enough. Although, an OLED or LCD can mimick LED displays and are more versatile. Have to factor in price too. 

Many things are still up in the air, but the hardware testing will help solidify many design choices. 

Next update should cover the hardware when it arrives.