OLSEN Rockmate Keio Korg 1966 vintage analog drum machine

Note: Auction links are affiliate links for which the site may be compensated.
via this auction
abertronix (RSS)

Pics of the inside below.

"Rebadged Keio Donca Matic Rock Mate, Keio being the name of the company before it became korg. This was made in the mid to late 1960's and is possibly the first portable drum machine manufactured.

It is a preset drum machine which runs off wither a 9v battery or 9v ac adapter. It has 6 basic rhythms A- F and an interesting "solo" button. This solo button seems to have 3 function but actually the way it works is (as it is a momentary type of switch) when you hold it down you get repeating 32nd notes - but if you manually press momentarily you can get 16th or quarter notes.

In any case this solo function enables you to varie the limited presets by a fair amount… its a wonder why this function didnt appear much on later units as it transforms a rather boring preset drum machine into something much more useful."