was one of Yamaha's early drum machines (maybe even their first?)
and as you can see from the panel cosmetics, it comes from the same
era as their DX synths.
At the time, it was a marvel - a (relatively)
low-cost programmable drum machine with 29 'real' drum samples and
no less than 12 individual audio outputs.
However, on the negative side, the pads were
just switches to trigger the sounds and there was no velocity sensitivity
- for dynamics, you had to use the 'accent' function. That said,
this was common for even the most expensive drum machines of the