I had a TRS-80 Color Computer and struggled with a cassette tape interface that was faster than many competitors but wasn't reliable for me. The disc drive I added was more expensive than the computer but it was reliable and could support the OS/9 operating system

https://en.wikipedia.org/wiki/OS-9

which was better than the MS-DOS I used later on the much more powerful 286 machine that replaced my Coco 3.