I'm not sure. A lot of year have passed. But I remember a ZX81 with 1K attached to a TV where I've learn to develop in basic and assembler. And also the Casio PB 100. A sophisticated programmable calculator. I'm not sure which one come first. But I really start to be involved in computer software developing with the Sinclair ZX Spectrum 48K. I still have one in my showcase completed with microdrives. Sinclair ZX Spectrum+[^] This is the plus version with an hard keyboard. Unfortunately I've lost the original one in some moving house

Saluti Emanuele