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QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
OS Components & Operations
Building Embedded Systems
The Building Embedded Systems guide is intended for developers who are developing or building BSPs for QNX Neutrino RTOS embedded systems.
IPL Library
The IPL library contains a set of routines for building a custom IPL.
uart_put
Output single character to UART (x86 only)

QNX Momentics IDE User's Guide
This User's Guide describes version 7.1 of the Integrated Development Environment (IDE) that's part of the QNX Momentics tool suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
- Quickstart Guide
- OS Components & Operations
  - Adaptive Partitioning User's Guide
  - Boot Optimization Guide
    The Boot Optimization Guide describes techniques you can use to reduce the time from your board's initial power on until you have a fully functional QNX system running on the board.
  - Building Embedded Systems
    The Building Embedded Systems guide is intended for developers who are developing or building BSPs for QNX Neutrino RTOS embedded systems.
    - Overview
      QNX systems are built from the QNX Neutrino RTOS standard release components, the architecture- and board-specific files provided in QNX BSPs, and customer and third-party components.
    - Working with QNX BSPs
      Before you attempt to write a new BSP or modify an existing one, it is helpful to know how to use a BSP.
    - Initial Program Loaders (IPLs)
      IPLs initialize the hardware, set up a stack for the C-language environment, load the OS image into memory, and finish up by jumping to the QNX startup code.
    - Startup Programs
      The first program to run in a bootable OS image is the startup code; it completes the system configuration, then launches the OS kernel.
    - Kernel Callouts
    - System Page
      The system page contains essential information about the system, including the system page's size, information about the hardware platform (including IRQs and the CPU), the cache size, and the location of kernel callouts in memory.
    - OS Images
      OS images are files that contains the OS, your executables, and any data files that might be related to your programs.
    - OS Image Buildfiles
      You can edit OS image buildfiles to configure OS images.
    - IPL Library
      The IPL library contains a set of routines for building a custom IPL.
      - enable_cache()
        Enable the cache
      - image_download_8250()
        Download an OS image
      - image_download_ser()
        Download an OS image
      - image_scan(), image_scan_2()
        Scan memory for a valid system image
      - image_setup(), image_setup_2()
        Copy the startup code and OS image into RAM and prepare it for execution
      - image_start(), image_start_2()
        Jump to the bootable OS image start point
      - init_8250()
        Initialize an 8250 serial port to 8N1 parameters
      - int15_copy()
        Copy data from high memory (above 1 MB) to a buffer, or to low memory (below 1 MB)
      - jump()
        Jump to the specifed in address in memory
      - print_byte()
        Output one byte to video (x86 only)
      - print_char()
        Display a character to video.
      - print_long()
        Display a long to video
      - print_sl()
        Displays to video a string, followed by a long (x86 only)
      - print_string()
        Display a string to video
      - print_var()
        Display a variable to video
      - print_word()
        Display a word to video
      - protected_mode()
        Switches the x86 processor to protected mode (non-BIOS systems)
      - uart_hex8
        Output an 8-bit hex number to the UART (x86 only)
      - uart_hex16
        Output a 16-bit hex number to the UART (x86 only)
      - uart_hex32
        Output a 32-bit hex number to the UART (x86 only)
      - uart_init
        Initializes the on-chip UART to 8 data bits, 1 stop bit, and no parity (8250 compatible)
      - uart_put
        Output single character to UART (x86 only)
      - uart_string
        Output a NULL-terminated string to the UART (x86 only)
      - uart32_hex8
        Output a 16-bit hex number to the UART (x86 only)
      - uart32_hex16
        Output a 16-bit hex number to the UART (x86 only)
      - uart32_hex32
        Outputs a 32-bit hex number to the UART (x86 only)
      - uart32_init
        Initializes the on-chip UART to 8 data bits, 1 stop bit, and no parity (8250 compatible)
      - uart32_put
        Output a single character to the UART (x86 only)
      - uart32_string
        Output a NULL-terminated string to the UART (x86 only)
    - Startup Library
    - Debugging QNX Embedded Systems
      The microkernel architecture of QNX Neutrino means that debugging QNX embedded systems can be different from debugging other embedded systems.
    - Sample Buildfiles
      This appendix contains sample buildfiles that you can modify to support your hardware platform and your implementation requirements.
    - Glossary
  - Core Networking Stack User's Guide
    This guide introduces you to the QNX Neutrino Core Networking stack and its manager, io-pkt.
  - Customizing a BSP
    While QNX provides Board Support Packages (BSPs) for many common platforms and their individual variants, in some cases, you need a BSP for a board that QNX does not provide. If this is the case, you can modify a QNX BSP or develop your own.
  - Device Publishers Developer's Guide
  - High Availability Framework Developer's Guide
  - High-Performance Networking Stack (io-sock) User's Guide
    This guide contains instructions for implementing and using the QNX Neutrino High-Performance Networking Stack and its manager, io-sock.
  - Instant Device Activation
  - Migrating to QNX SDP 7.1
  - PCI Server User's Guide
  - Persistent Publish/Subscribe Developer's Guide
  - Platform-independent Publish/Subscribe Developer's Guide
    This guide is intended for application developers who want to use the Platform-independent Publish Subscribe (PiPS) framework to exchange information with other applications. First, the overall PiPS design and data-exchange model are explained. Then, tutorials on using PiPS are given. These tutorials cover key tasks such as selecting a publish-subscribe provider to use and writing plugins that read and write custom data types.
  - QDB Developer's Guide
  - QNX Helpers Developer's Guide
    These libraries provide QNX helpers, including helpers that assist with logging, string conversion, and number and type sizes.
  - SMMUMAN User's Guide
  - System Analysis Toolkit (SAT) User's Guide
  - System Architecture
    The System Architecture guide accompanies the QNX Neutrino RTOS and is intended for both application developers and end-users.
  - Technotes
  - User's Guide
    The QNX Neutrino User's Guide is intended for all users of a QNX Neutrino RTOS system, from system administrators to end users.
- Audio & Graphics API
- Multimedia
- Networking Middleware
- Programming
- Sensor Framework
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX Neutrino RTOS system and developers who want to create a QNX Neutrino resource manager free from vulnerabilities.
- Utilities & Libraries
QNX Hypervisor
The QNX Hypervisor allows you to run multiple OSs on a target system so you can separate critical and non-critical functions, support a wide variety of applications, and reduce hardware costs.
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX software in Amazon Web Services (AWS) and Microsoft Azure (Azure).
QNX Advanced Virtualization Frameworks User's Guide
This User's Guide is aimed at all systems integrators and developers who want to design and build embedded systems using the QNX Advanced Virtualization Frameworks.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation and explains how to obtain technical support.

uart_put

Output single character to UART (x86 only)

Description:

This assembly call outputs a single character to the UART. The function is set up for a 16-bit real-mode environment. It is supported only for x86 platforms.

On entry:

AL: Character to output.
DX: UART base port.

Page updated: March 12, 2026