Term
| What is a real-time system |
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Definition
| Real-time systems must satisfy explicit (bounded) response-time constraints or risks severe consequences, including system failure. |
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Term
| What is a control system? |
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Definition
| Used to control physical processes to obtain predefined objectives within tolerances. |
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Term
| What is a real-time control system? |
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Definition
| A real-time control system must meet its control objectives within specific timing constraints (deadlines). |
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Term
| What is a computer control system? |
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Definition
| A digital control system. |
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Term
| What are the classes of real-time systems? (3 points) |
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Definition
| Soft, hard, Firm real-time systems |
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Term
| What is a soft real-time system? |
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Definition
| A soft real-time system will tolerate such lateness, and may respond with decreased service quality |
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Term
| What is a hard real-time system? |
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Definition
| The completion of an operation after its deadline is considered useless - ultimately, this may lead to a critical failure of the complete system |
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Term
| What is a firm real-time system? |
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Definition
| Some deadlines can be tolerated.. but if beyond certain point, system fail |
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Term
| What are the features of a real-time system? |
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Definition
Predicably fast response to urgent events
High degree of schedualbility
Stability under transient overload |
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Term
| Name the three specialized processors. |
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Definition
RISC (Reduced Instruction Set Computer)
Parallel processors (SIMD - single instruction path multiple data path, MISD - multiple instruction path single data path, MIMD - multiple instruction path multiple data path)
Digital signale processors (typically: separate data and instruction paths) |
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Term
| Explain the different types of external signals that a computer control system may have to deal with. |
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Definition
Digital: Usually in binary format (e.g. For on/off status). Other binary codes (e.g. ASCII, BCD, etc.) are possible.
Analog: Usually the measurement values of analog devices (e.g. Strain gauges, potentiometers, etc.).
Pulses: Usually from measuring instruments that provides readings in the form of pulse trains (e.g. Stepper motors, flow meters, etc.). |
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Term
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Definition
| Generates events at a specific time or measures the duration between two events. |
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Term
| What is a counter used for? |
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Definition
| Used to count pulses on other signals. |
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Term
| What is a watchdog timer? |
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Definition
| It monitors time outs by generating an error signal if a signal is not received within a specified time period. |
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Term
| What is a DMA controller and how does it work? |
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Definition
DMA (Direct Memory Access) controller allows I/O devices to transfer data directly with the memory.
1. CPU sets up DMAC by specifying the memory address and amount of data to be transfered
2. transfer takes place directly between the memory and I/O device while the CPU can preform other jobs during the transfer |
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Term
| What are the two DMA modes? |
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Definition
Burst - DMA controller takes over the data bus to transfer a block of data
Single-cycle/Cycle stealing - DMA controller takes occasional machine cycles from the CPU to transfer a byte of data |
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Term
|
Definition
| Real-time systems must satisfy explicit (bounded) response-time constraints or risks severe consequences, including system failure. |
|
|
Term
| What is a control system? |
|
Definition
| Used to control physical processes to obtain predefined objectives within tolerances. |
|
|
Term
| What is a real-time control system? |
|
Definition
| A real-time control system must meet its control objectives within specific timing constraints (deadlines). |
|
|
Term
| What is a computer control system? |
|
Definition
| A digital control system. |
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|
Term
| What are the classes of real-time systems? |
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Definition
| Soft, hard, Firm real-time systems |
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