Yamaha TX81Z

The RAM slots were rarely utilized[citation needed] due to the perceived high quality and usability of the original patches and the difficulty of programming new sounds with the limited front-panel interface.

[1] It is also very similar, and almost completely patch-compatible, to the DX11 synthesizer, which is essentially a TX81Z with a velocity and pressure-sensing keyboard and a pitch envelope.

[1] Creating new sounds from the unit's front panel is possible, but numerous nested parameters must be navigated by way of 11 buttons and a backlit 16 character, 2-line LCD.

The Dutch company KissBox released in 2013 a TX81Z editor based on RTP-MIDI communication, which makes the hardware synth appear as a VST plugin, while being controlled over a network link in real-time.

A 63B03 CPU allocates voices and generates auxiliary LFOs, in parallel with MIDI and user interface, which might be why e.g. a pitch EG was omitted; the later DX11 splits responsibilities between 2 CPUs and adds a PEG.