---
title: Tilde manipulation of the DIRA and OUTA registers
description: "[SPIN](https://obex.parallax.com/code-language/spin/) #### Introduction The Propeller Spin language uses the single-tilde and double-tilde suffixes for compact single-bit manipulation on the DIRA and OUTA registers. These are **single-bit assignment** operations that work only for the DIRA and OUTA registers and are an…"
url: "https://obex.parallax.com/docs/chips-tips/propeller-1/tilde-manipulation-of-the-dira-and-outa-registers/"
updated: "2025-10-08"
category: Propeller 1
---

# Tilde manipulation of the DIRA and OUTA registers

[SPIN](https://obex.parallax.com/code-language/spin/)

#### Introduction

The Propeller Spin language uses the single-tilde and double-tilde suffixes for compact single-bit manipulation on the DIRA and OUTA registers.

These are **single-bit assignment** operations that work only for the DIRA and OUTA registers and are an extremely concise way to set or clear a bit.

#### DIRA

The command `dira[Pin]~~` sets the direction of the specified I/O pin to **Output** mode.

- **Function:** It sets the corresponding bit in the DIRA register to **1**.
- **Result:** The pin is configured as an **Output**, allowing its state to be driven HIGH or LOW by the OUTA register.
- **Equivalent:** The `dira[Pin]~~` command is shorthand for the standard assignment: `dira[Pin]`:=1

| Command | Action | I/O Function | Traditional Equivalent |
| --- | --- | --- | --- |
| dira[Pin]∼ | Set LOW (Clear Bit) | Input | dira[Pin]:=0 |
| dira[Pin]∼∼ | Set HIGH (Set Bit) | Output | dira[Pin]:=1 |

#### OUTA

The command `outa[Pin]~` forces the state of the I/O pin specified by `Pin` in the **output register (OUTA)** to **0 (LOW)**.

- **Function:** It sets the corresponding bit in the OUTA register to**0**.
- **Result:** The pin is driven LOW when the DIRA register is set to output.
- **Equivalent:** The `outa[Pin]~` command is shorthand for the standard assignment: `outa[Pin]`:=0

| Command | Action | Bit Value | Traditional Equivalent |
| --- | --- | --- | --- |
| outa[Pin]∼ | Set LOW (Clear Bit) | 0 | outa[Pin]:=0 |
| outa[Pin]∼∼ | Set HIGH (Set Bit) | 1 | outa[Pin]:=1 |
| outa[Pin]∧=1 | Toggle (XOR) | Toggle | outa[Pin]∧=1 |

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## Resources

[Parallax Community Forums](https://forums.parallax.com)

[Parallax Propeller 1 Manual](https://www.parallax.com/package/propeller-manual)

[Parallax Propeller 1 Documentation](https://www.parallax.com/download/propeller-1-documentation)

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