From Sega Retro
The SC-5000 (Sega Computer-5000) is an extremely rare update to Sega's SC-3000 computer. The third model in the series (following the SC-3000 and SC-3000H), the SC-5000 boasts improved specifications and is assumed to have surfaced around 1984.
Very little is known about the SC-5000, other than it exists. It is very unlikely the system was sold oustide of Japan.