There are two functional blocks - a ring oscillator with multiple taps, and a glitchless clock switch.
To test the oscillator - Input 0 is input to first inverter in the oscillator. One of the inverted outputs either 0 (slowest), 1 (mid), or 2 (fastest) should be connected to input 0. To test the clock switch - input 1 selects between clock0 (on input 2) and clock 1 (on input 3). Selected CLK appears on OUT3
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | 0 Osc In | 0 OSC OutSlow/segment a | |
| 1 | 1 ClkSel | 1 OSC OutMid/segment b | |
| 2 | 2 CLK0 in | 2 OSC OutFast/segment c | |
| 3 | 3 Clk1 in | 3 ClkOut/segment d | |
| 4 | segment e | ||
| 5 | segment f | ||
| 6 | segment g | ||
| 7 | dot |