|  | CMSIS-RTOS
    Version 1.03
    Real-Time Operating System: API and RTX Reference Implementation. | 
This section lists the technical data of CMSIS-RTOS RTX.
| Description | Limitations | 
|---|---|
| Defined Tasks | Unlimited | 
| Active Threads | 250 max | 
| Mailboxes | Unlimited | 
| Semaphores | Unlimited | 
| Mutexes | Unlimited | 
| Signals | 16 per thread | 
| Timer Callbacks | Unlimited | 
| Code Space | < 5.0 Kbytes | 
| RAM Space for Kernel | 300 bytes + 128 bytes Main Stack | 
| RAM Space for a Thread | StackSize + 52 bytes | 
| RAM Space for a Mailbox | MaxMessages * 4 + 16 bytes | 
| RAM Space for a Semaphore | 8 bytes | 
| RAM Space for a Mutex | 12 bytes | 
| RAM Space for a User Timer | 24 bytes | 
| Hardware Requirements | SysTick timer or other hardware timer | 
| Thread context switch time | < 2.6 usec @ 72 MHz | 
| Interrupt lockout time | Not disabled | 
The generic wait function osWait is currently not supported by CMSIS-RTOS RTX.