MOS Technology TED

It was a video chip that also contained sound generation hardware, DRAM refresh circuitry, interval timers, and keyboard input handling.

This tone generator was designed for business applications, and did not provide the extensive sound features found in the SID chip.

The chip also contains an I/O port, which is used on the Plus/4 and 16 to control the IEC bus (for connecting Floppy Disk Drives) and the Datassette (Tape Recorder).

Thus in the borders the CPU is able to run at full speed, but in the active display area it is throttled down to half the clock rate.

[4] As TED chips are not produced anymore, its internal architecture has been investigated and replicated by Hungarian developer Istvan Hegedus using verilog HDL in a project called FPGATED.

There was another TED replacement in development based on the original source code by the "ThED project", but this has been put on hold because of difficulties with component supplies.