W65C816S pinout
The 40 pins of the processor in its DIP40 package, and what each one will be connected to.
| Pin | Signal | Connection |
|---|---|---|
| 1 | VPB | not connected, test point |
| 2 | RDY | 9K as open drain and expansion, 3.3 kΩ pull-up to 3.3 V |
| 3 | ABORTB | 10 kΩ pull-up to 3.3 V (mandatory) |
| 4 | IRQB | wired-AND interrupt line, 3.3 kΩ pull-up |
| 5 | MLB | not connected, test point |
| 6 | NMIB | wired-AND non-maskable interrupt line, 3.3 kΩ pull-up |
| 7 | VPA | 9K |
| 8 | VDD | 3.3 V, 100 nF capacitor as close as possible |
| 9 – 20 | A0 – A11 | 9K; A0 – A4 also to the 20K, the Pico and the expansion |
| 21 | VSS | ground |
| 22 – 25 | A12 – A15 | 9K |
| 26 – 33 | D7 – D0 | shared data bus |
| 34 | RWB | 9K, 20K, Pico, direction of the expansion buffers |
| 35 | E | not connected, test point |
| 36 | BE | 9K, 10 kΩ pull-down to ground |
| 37 | PHI2 | clock output of the 9K |
| 38 | MX | not connected, test point |
| 39 | VDA | 9K |
| 40 | RESB | 9K, 10 kΩ pull-down to ground |
Key points
- RDY is never driven as an active output: the
WAIinstruction pulls it low itself. - IRQB and NMIB are pulled as open drain by the 20K, the Pico and the expansion, without going through the 9K.
- BE and RESB are pulled to ground: at start-up, the processor stays off the bus and in reset until the 9K releases it.
- The memory (PSRAM) is connected only to the 9K: no processor pin goes to it directly.
For the role of each signal, see The processor and the bus.