Monitor Program Critique Wanted!

Programming the 6502 microprocessor and its relatives in assembly and other languages.
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BigDumbDinosaur
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Re: Monitor Program Critique Wanted!

Post by BigDumbDinosaur »

JimBoyd wrote:
A jump table is a way to future proof your design.

Probably the best-known use of a jump table is in the Commodore “kernal,” which every eight-bit Commodore machine has had.
x86?  We ain't got no x86.  We don't NEED no stinking x86!
Sean
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Joined: 15 Feb 2021

Re: Monitor Program Critique Wanted!

Post by Sean »

Absent a software interrupt capability, it seems a good approach. Are there others?
BigDumbDinosaur wrote:
JimBoyd wrote:
A jump table is a way to future proof your design.

Probably the best-known use of a jump table is in the Commodore “kernal,” which every eight-bit Commodore machine has had.
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barrym95838
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Re: Monitor Program Critique Wanted!

Post by barrym95838 »

Several of the 6502 pioneers like Woz didn't bother with JMP tables or complex BRK handlers, although convoluted RTS tables were definitely on the menu. They packed their ROM code as tightly as they possibly could, and let the entry points fall where they may. Many of those entry points became "standard", like the Apple ]['s $FDED for COUT and -151 for the monitor prompt, and the burden fell on the person updating the ROM code in subsequent incarnations to keep that functionality as well as he or she could. When you're a pioneer (or just want to act like one), you can be afforded some artistic license in my book.
Got a kilobyte lying fallow in your 65xx's memory map? Sprinkle some VTL02C on it and see how it grows on you!

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