A polyphonic synth with patch memory, originally designed by ARP Instruments in the late 1970s, but eventually manufacturered and marketed by CBS Musical Instruments. The Chroma was a product of the turbulent late-'70s years at ARP when money was running short and dissention existed among the leadership as to the direction of the company. Al Pearlman and Philip Dodds favored spending R&D money on the Chroma, but a faction including David Friend wanted to develop the Avatar guitar synthesizer. Friend's faction won and Chroma development work was continually pushed back in favor of putting resources into the Avatar.
The Avatar turned out to be a market flop when it was introduced in 1979, and that put ARP into severe financial straits. The Chroma developers, working with limited resouces, managed to produce a prototype of the Chroma, but ran out of time on the production version when ARP went bankrupt in 1981. The bankruptcy court appointed Dodds executor of the company's liquidation, and Dodds arranged for the rights to the Chroma design to be sold to CBS; he then transferred himself and most of the Chroma team to CBS.
They built the first production Chromas in 1982, hand-wiring the first 50 in their lab while they tried to work out some production-line kinks. The synth eventually went into mass production using a Kimball organ factory owned by CBS. Wanting to sell the synth under a brand name that would be familiar to the target audience, CBS marketed it under the Rhodes brand (despite the fact that electric-piano innovator Harold Rhodes had nothing to do with it). The Chroma contained a number of innovations for its time, including a computer interface port which allowed for patch editing and sequencing. (Later production units also had MIDI.) A notable quirk was the "thunker", a solenoid that tapped a rod against the inside of the wooden case to acknowledge user input
The Chroma was a modest hit and about 4000 were produced through 1986. The group also produced a Chroma Expander (basically a Chroma with no keyboard), and the Chroma Polaris, a lower-cost version with a membrane panel (which has become a headache for owners due to deterioration of ribbon cables molded into the panel). These were the only synths ever marketed under the Rhodes name. Development and production ceased when CBS liquidated the Musical Instruments division in 1987. Chromas have moderate-high value among collectors, Chroma Polarises less so due to the membrane panel problem.