ForeverSublime:
The MSX home computer had an official release in Dec 2001.
But consider the gap of time and if the games are home brew, CGE has a few releases on really old systems. Back to:
PC-Engine - It started in 1987, but the last game made in early 1999, Dead of the Brain 1 & 2, requires Super CD-Rom, which is basicly the hardware upgrade released back in 1992, so you'd have to count from that point.
Game Boy - Count the last Game Boy Color game, which you can still play on the very first Game Boy unit the end of Game Boy run, once they stop making GBC games, the streak is over.
So there you have it, Neo-Geo, 13 yrs and still going. You still use the same system bought back in 1990. Back in 1994 when I bought first AES system in Funcoland, a store clerk told me why I wanted Neo-Geo instead of Sega CD, NG would be dead soon, he said.
This is first time we get a really good thread and discussion.