Two DCO/voice version of SX-210 in many respects. They use 8253 programmable timers for DCO's and two CPU's to control the various facilities. Subtractive with digital controlled/generated oscillators and dial/button select data entry.
Bad solder galore in the one I worked on. The battery is likely to spill caustic stuff. They placed these better than in some machines but STILL things can get damaged so watch out!
More recently one had a power supply problem that let 5V hit 7.5V or so. The CPU apparently was damaged as after I replaced the buzzer stayed on all the time instead of intermittently. The last problem though was line SAD6 being clamped in some way by the .3" 6116 chip by the slave EPROM. Just have to cut traces and patch them back in such instances to confirm what is causing the problem since they aren't socketed except EPROM on that one.
I should have many parts for these. Contact me if you need something.