Add readme for the pal pod

board/dupico_pods/pod_pal/README.md

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+# DuPAL board
+
+## DISCLAIMER
+
+Any use of this project is **under your own responsibility**.
+You will be responsible of checking the correct construction and functionality of your board and the compatiblity of the chips You will insert into it.
+By using this project You will agree that I cannot be held responsible if it will destroy any of your devices, damage your computer, burn down your house or whatever.
+
+**Do NOT come to me for hand-holding** using this. It is NOT a plug-and-play tool, and it is something I created **for my own use** and I released in case someone might have an use for it.
+
+## Introduction
+
+The PAL POD is an adapter for the DuPAL V3 (AKA "dupico") meant to support 20 and 24 pin PAL (and pinout compatible) devices.
+
+![Rev. 0 PCB](pics/pal_pod.jpg)
+
+### Usage
+
+This device must me inserted in the ZIF socket of the dupico: if you installed a ZIF42 socket, it will fill all the 42 pins, if you installed a 48 pin socket, make sure to leave the bottom 6 pins empty (fit this in the topmost part of the socket).
+
+When you fit a PAL device in it, make sure to align it to the bottom of the ZIF24 socket (so, a 20 pin device will leave empty the topmost 4 pins in the socket). 
+
+**Pulling high pin 22 of the ZIF42 socket will turn on the transistor on the pod, which in turn will provide 5V to pin 22 of the ZIF24 socket**, pin 12 is hardwired to GND, and pin 24 to VCC.
+
+#### Socket connections
+
+This drawing shows how the pin on the ZIF24 sockets are wired to the pins on the dupico's ZIF42.
+
+```
+            __ __
+   1 ---> 1   U  24 <--- +5V
+   2 ---> 2      23 <-- 41
+   3 ---> 3      22 <-- 40 --- 5V if ZIF42 pin 22 is HIGH
+   4 ---> 4      21 <-- 39
+   5 ---> 5      20 <-- 38
+   6 ---> 6      19 <-- 37
+   7 ---> 7      18 <-- 36
+   8 ---> 8      17 <-- 35
+   9 ---> 9      16 <-- 34
+  10 --> 10      15 <-- 33
+  11 --> 11      14 <-- 32
+GND ---> 12______13 <-- 31
+
+```
+
+## Hardware
+
+The board was designed with [KiCad](https://kicad.org/) EDA.
+
+In its current form, the board is relatively simple build, using through-hole and (non fine pitched) SMD components.
+
+
+### Bill of Materials
+
+| Component         | Qty | Type / Value                   | Notes                                                    |
+| ----------------- | --- | ------------------------------ | -------------------------------------------------------- |
+| J1                |  2  | 21 pin 2.54mm headers          | Use rounded pin headers to put less stress on dupico ZIF |
+| C1, C2            |  2  | 100nF / 1206 / ceramic         |                                                          |
+| JP1               |  1  | 2 pin 2.54mm header            | Optional, bypasses the transistor                        |
+| Q1                |  1  | 2N3906 TO92                    |                                                          |
+| J2                |  1  | narrow ZIF24 socket            | Solder this AFTER the two J1 headers                     |
+| U1                |  1  | 74HCT04 SOIC-14                | https://www.mouser.it/ProductDetail/771-74HCT04D-Q100118 |
+