Atari 400 was my first, too. First program I wrote in BASIC, I ran out of memory. Upgraded to Atari 800 with 48K. I still have that one. Back in the day I would buy old game cartridges and unsolder the ROM and replace it with an EPROM and then burn games from magazines like A.N.A.L.O.G. to the EPROM. The EPROM burner plugged into the joystick ports of the Atari. My first foray into assembly language programming was with the Atari.

I also started as a Mechanical Engineer in the defense industry. Got into Finite Element Analysis and did quite a bit of FORTRAN programming. When the personal computer era started up, I learned assembly programming (my first computer was an Atari 400). Bought an IBM PC when they first came out. I moved into automated manufacturing doing programming using Pascal and C. Then moved on into C++ and now do C# and web app development.