|OS family||Real-time operating systems|
|Source model||Open source|
|Initial release||1985 (age 28–29)|
|Latest release||6.40.02.27 / June 2014|
|Marketing target||Embedded systems|
|Platforms||TMS320 DSPs, ARM, MSP430|
SYS/BIOS is a real time operating system created and offered by Texas Instruments (TI) for use in a wide range of their embedded processors. SYS/BIOS is a component of TI’s Code Composer Studio integrated development environment.
SYS/BIOS provides a wide range of system services to an embedded application such as preemptive multitasking, memory management and real-time analysis. Because SYS/BIOS can be used in such a wide variety of different microprocessors with very different processing and memory constraints, it was designed to be highly configurable.
The roots of SYS/BIOS were originally developed by Spectron Microsystems (a subsidiary of Dialogic Corporation) as the first real time operating system developed specifically for digital signal processors and was named SPOX. Spectron Microsystems eventually also developed a second product called BIOSuite that included a light-weight real time kernel and various associated tools that allowed for configuration and real-time analysis.
Spectron Microsystems was eventually acquired by Texas Instruments  and the SPOX and BIOSuite products were combined into a single microkernel product called DSP/BIOS. With the release of version 6.3, DSP/BIOS was renamed to SYS/BIOS in order to reflect its support for microcontrollers beyond DSPs.
SYS/BIOS is released under the BSD License and any user can build the kernel from the included source code.
The SYS/BIOS software product is made up of a number of discrete components, called modules. Each module can provide services via an API and is individually configurable. For example, system semaphores are provided by a module called ti.sysbios.knl.Semaphore and the developer can choose whether this module is included in the runtime image or optimized out. If the module is included, the user can configure various aspects of the Semaphore module and can also configure instances of semaphores to be created as soon as the system starts up. The Semaphore module also provides an API so that semaphores can be created, posted, pended and deleted while embedded program runs.
SYS/BIOS provides support for several different types of threads in an embedded system.
- Hardware Interrupt (Hwi): support threads initiated by a hardware interrupt.
- Software Interrupt (Swi): structured to be similar to Hwis, but allow processing to be deferred until after a hardware interrupt has completed.
- Task: a discrete thread that can execute or block while waiting for an event to occur.
- Idle: the lowest priority thread that only runs when no other thread is ready to execute.
SYS/BIOS provides tooling to set up an embedded system’s memory map and also to allow memory buffers to be allocated and deallocated while the system runs. The type of memory manager used during runtime is actually configurable so that memory fragmentation can be minimized if necessary.
Real time debugging
SYS/BIOS provides modules that allow it to provide information about how the system is executing. This includes how different threads are loading the CPU over time as well as logging events as they occur in both the system application as well as within SYS/BIOS itself. In addition, the Code Composer Studio integrated development environment can take this logged data and graphically display it for the developer.
- Press Release January 22, 1998
- SYS/BIOS category page on TI wiki
- SYS/BIOS software page on TI website
- SYS/BIOS User's Guide (link to latest version)
- SYS/BIOS Downloads
- DSP/BIOS category page on TI wiki