I had a PC jr. The base model, which I had, came with 128k of memory, a single 5.25" inch floppy, and 2 cartridge slots. I booted DOS via a cartridge. There

I had a PC jr. The base model, which I had, came with 128k of memory, a single 5.25" inch floppy, and 2 cartridge slots. I booted DOS via a cartridge. There was an expansion unit you could purchase which had a 2nd floppy (very handy!) and I think it expanded max memory to 640k (but might have only been 256k).