My first computer was also a TI99A4, w/o extended module, my brother gave it to me in 1985, the next was an C64 with casette and later the 1541 floppy following by the C128D (sounds like a Hoover) next was the Atari 520ST+ but not long - about half a year then i get the ultimate machine AMIGA 1000 and at the last comes normaly PC's i begin with 486DX66.
My first computer i don't have anylonger i give it back to my brother and i think he still have it? My C64 and my Amiga still there and a Atari STF1040 also but no time to use it because there is another hobby (my old tube radios)
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Regards Martin