That's what makes TSRs possible. A TSR is essentially just an ordinary program, the only difference is that when it exits, it tells the OS to leave the process in memory rather than unloading it.
Yeah, I remember programming a bunch of those in TurboPascal. There were compiler directives to limit the heap size and some inline assembly was needed to save/restore the stack inside the interrupt handler, but once it worked, the rest was like a normal program.
It was very useful to have a calculator, taking notes, etc. Now we take multitasking for granted, of course.
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That's what makes TSRs possible. A TSR is essentially just an ordinary program, the only difference is that when it exits, it tells the OS to leave the process in memory rather than unloading it.
Yeah, I remember programming a bunch of those in TurboPascal. There were compiler directives to limit the heap size and some inline assembly was needed to save/restore the stack inside the interrupt handler, but once it worked, the rest was like a normal program.
It was very useful to have a calculator, taking notes, etc. Now we take multitasking for granted, of course.