# Coldcard Internal Documentation

These docs are meant for you hackers out there... but also for anyone who
wants to understand why it's safe to put your moneys into Coldcard.

- [`pin-entry.md`](pin-entry.md) Huge and detailed discussion of PIN codes and the security element that holds the secrets.
- [`dev-access.md`](dev-access.md) How developers can modify Coldcard to extend it.
- [`memory-map.md`](memory-map.md) Memory map highlights
- [`backup-files.md`](backup-files.md) Some details of our encrypted backup files.
- [`electrum-usage.md`](electrum-usage.md) Importing seed words into Electrum for funds usage (and other tips).
- [`bitcoin-core-usage.md`](bitcoin-core-usage.md) How to use with Bitcoin Core.
- [`limitations.md`](limitations.md) Documented limitations, policy choices, and TODO items.
- [`paperwallet.pdf`](paperwallet.pdf) Example paper wallet template file.
- [`seed-xor.md`](seed-xor.md) More about _Seed XOR_ feature, including fully worked Seed XOR example, and useful XOR lookup chart.
- [`menu-tree.txt`](menu-tree.txt) Dump of the menu system. Incomplete, may be out of date.
- [`nfc-coldcard.md`](https://github.com/Coldcard/firmware/blob/master/docs/nfc-coldcard.md) NFC Specification for COLDCARD interoperability.