My childhood as well! In 6th and 7th grade my parents would drop me off at the mall 9am on Saturday and pick me up around 5pm. I spent all day at the Radio Shack (and a bit of time at the arcade after lunch). Learned to program in BASIC on the Model III and the CoCo and wrote all kinds of demo programs. They tolerated me there all day since I was also happy to talk to customers and show them how the computers worked and how to write simple programs.
By end of 7th grade I'd saved enough money to buy a CoCo to program at home, so my long days at Radio Shack came to an end but I'd still drop by for a bit every weekend.
One of the lesser known and vastly underrated systems of the 80s was a CoCo running OS-9, a multiuser multitasking operating system on an 8-bit CPU! OS-9 Level 2 was particularly powerful, and prepared me to move seamlessly to SunOS when I started university.