Update via joseph_amos in the comments: "This is actually a DIY project. [link] It looks like whoever is selling just copied and pasted the text from the first page. "images via this auction
"serial No. 001 t page 2002
The 9090 is an analogue drum machine based upon the legendary Roland TR-909 Rhythm Composer. Many people consider this machine to be the life and soul of house music and it's modern derivatives. Trance, techno, whatever. In some moment of insanity back in '99 I decided it would be a fun challenge to build an entire clone of this classic analogue drum box (having no appreciation of how such a project can take over your life) and, bored with using sampled beats, I wanted a real, tweakable analogue box. Just like the 909.
I chose to make my 9090 just a MIDI controlled unit without an integral sequencer. All original drums are in there, together with power supply and a new PIC-based MIDI interface. The complete project is built across two separate printed circuit boards, designed to fit within a 2U height 19" rack enclosure. I didn't develop a sequencer to go with this, but I'll do it if I get the time.
The voice circuits used within the clone remain faithful to those of the original machine. In other words they remain mostly unchanged, except where I've added controls for extra tweakage. Most semiconductors have been substituted for modern equivalents that are more easily available. Most of the TR-909 sounds are completely analogue and hence some pretty intricate discrete circuitry is involved. Only the hi-hat and cymbal are 'digital' since the TR-909 used samples contained within three 32K ROMs for these.
