ST20-C1 STMICROELECTRONICS [STMicroelectronics], ST20-C1 Datasheet - Page 194

• Manufacturer Part Number: ST20-C1
• Description: Instruction Set Reference Manual
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Task
Task descriptor
Tdesc
Thread
Timeslice
Trap
Trap handler
Trapped
Unsigned value
Vector
Waiting
Word
Word-aligned
Work space
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bits are global and are preserved when a process is descheduled and others are
local to a process and are lost when the process is descheduled .
A process .
The identifier of a process , which is a pointer to the process descriptor block .
When a process is executing, the Tdesc holds the task descriptor of the process.
A 32-bit register which holds the task descriptor of the current process .
A dynamically generated process .
Deschedule a process to allow other processes access to the CPU. Timeslicing
prevents any one process from occupying too much CPU time. A timesliced
process is normally added to the back of the scheduling queue and the process on
the front of the queue is restarted.
An exception caused by software, or an interrupt initiating a scheduling event.
The code and data which define what happens when a trap is taken.
A process is trapped when it is waiting for a trap handler to complete.
Value which could only be positive, so the most significant bit is not used as a sign
bit .
An array .
A process is waiting for an event if it cannot continue execution until that event has
occurred. The event could be for example a communication or a semaphor e
signal.
A word is a four byte (32-bit) location for data.
An address is word-aligned if it is divisible by 4, i.e. if the least significant two bits
are zero.
Space in memory for local variables and values.