Jameco Electronics 3000, 2000 manual User’s Manual

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ded applications. Some applications may require large data arrays or tables that will require additional data memory. For this purpose Dynamic C supports a type of extended data memory that allows the use of additional data memory, even extending far beyond a megabyte.

Requirements for stack memory depend on the type of application and particularly whether preemptive multitasking is used. If preemptive multitasking is used, then each task requires its own stack. Since the stack has its own segment in 16-bit address space, it is easy to use available RAM memory to support a large number of stacks. When a pre- emptive change of context takes place, the STACKSEG register can be changed to map the stack segment to the portion of RAM memory that contains the stack associated with the new task that is to be run. Normally the stack segment is 4K, which is typically large enough to provide space for several (typically four) stacks. It is possible to enlarge the stack segment if stacks larger than 4K are needed. If only one stack is needed, then it is possible to eliminate the stack segment entirely and place the single stack in the data seg- ment. This option is attractive for systems with only 32K of RAM that don’t need multiple stacks.

User’s Manual

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Jameco Electronics 3000, 2000 manual User’s Manual