50g

The calculator only has 1.5 MB of memory for programs if distributed amongst Ports 0, 1, and 2 I think. At any rate the place where you'd logically store programs (the HOME directory) is actually RAM, limited to 241 KB. Anytime RAM has a slight hiccup in its operation the calculator dumps everything. It's kind of cool. The whole screen starts to fizzle with little black dots, and then everything is gone. So, its time to start using SD cards. The calculator will format unformatted SD cards in FAT32 and excepts either FAT16 or FAT32 but most cards are already formatted. First, of all there are a lot of SD cards out there, which one is the right size and who has them? Second, how much memory can the card have? Once the card is working, can you change the directory to Port 3 and/or a subdirectory in Port 3 and have it remain there until it's changed again like in the other directories or do you have to type some cryptic code to gain access to objects in Port 3 subdirectories under the same directory you in? And lastly, when you fill up a large SD card, and have concerns about backing it up with another, how do you do it without being able to transfer it to the calculators existing memory? If you make a copy of the SD card using the computer, how is this done given that your computer has a MMC/SD card slot i.e. is it simply highlight it and click on copy?