From Yamaha Wiki
The Yamaha DX11 was one of the later models of the legendary DX series that Yamaha produced in the 1980s. The DX11, released in 1988, four years after the DX7, offered 8-part Multitimbrality, a feature absent from previous DX synthesizers (like the DX7 or DX9).
The DX11 had 8-note polyphony, and was based around a 4-Operator digital FM synthesizer (like the DX9, in contrast with the DX7, which had 6 operators), and also offered an LFO, simulated Reverb, DDL delay, pan and tremolo. The DX11's multitimbral features allowed players to spread various sound patches across different "zones" of the keyboard. It also allowed complex ensemble performances using external sequencers, or while playing live using "Performance" patches.
The "Quick Edit" function was a helpful utility for programming sounds (a more laborious process on the DX7 or DX9); thus the user did not have to delve into the complexity of FM synthesis in order to make a few simple changes to a sound. These quick edits affected the tone, envelope attack and release times. Unfortunately, there were no on-board arpeggiators or sequencers. The DX11 had 61 keys (with velocity and aftertouch sensitivity), and its memory included 128 preset patches and 32 performance patches. It also had a slot for external cartridge memory (holding 64 patches) and a cable for connection to a cassette deck for data transmission and reception.