A cheap digital sampling synth with simple envelopes, and some ROM samples. Beautifully quirky. The Sk-5, SK-8(A), SK-10, SK-60, Sk-100, SK-200, SK-2100 and some other misc keyboards are on the this SK site
They all have a bug. If you leave them plugged in they do strange things and default on by themself but..not really. Just the kind of 'on' where they make annoying sound in the mix that you don't know where it's coming from. They auto-turn off also and lose any data after 5 minutes. But for a buck fifty what do I expect? :-) Can't believe what these sell for again. 80 bucks sometimes!? If you WANT TO DEFEAT THE ANNOYING AUTO-POWER OFF...simply cut line from pin 86 on the MSM-6283 cpu. THen tie the other side to a 10K resistor that has the other side tied to V+ so it holds the line formerly tied to the cpu high. See the SK series page for details on how to defeat it on the SK-5.
Easy to come by on ebay. Ok now they sell for too much. Should have gotten a spare when they were 1.50 at the thrift store.