MSX wasn't one computer but a standard, dreamed up by Kazuhiko Nishi of ASCII Corporation with Microsoft. Any maker could build a machine to it, and every MSX game and cartridge would work on all of them.
Dozens of companies did. MSX ruled in Japan and was popular in the Netherlands, Spain and Brazil, and it was the first home for several famous game series.
Fifteen colours plus transparent. In its main graphics mode each row of 8 pixels could hold only two colours. It had 32 hardware sprites, one colour each, and only four could share a line, so games layered sprites for more colours and flickered when they crowded together.
The AY-3-8910 had three square-wave channels and a shared noise generator, plus a hardware envelope that could make buzzing bass and simple drum sounds. Later MSX machines and cartridges added FM synthesis.