With the purchase of a C116 off Ebay I now have my Commodore 264 series complete. OK, there exist a few prototypes of the V364, but it never went in production. In the picture from the top: Plus/4, the tiny C116 and the C16.
The 264 series is a one-chip design. The chip is called TED (Text EDitor), the MOS 7360. It was presented in 1984 when the C64 still was very popular. It was not compatible with the C64. It had some nice features, like BASIC 3.5, but almost no periferals of the C64 worked with the 264.
The C116 was a small presentation of the C16 with the same specification: 16Kb only, while the Plus/4 had 64Kb. Being cheap and with it's rubber keyboard the C116 should have been a Spectrum ZX-killer. But it failed, as all 264 series computers failed. The C16 had the same breadbin case as the VIC-20 and C64.
The Plus/4 even had built in office software: word processor, spreadsheet, database and graphics programs. But it all was buggy and limited in use.