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3619RE: Anyone decompile AltairDOS?

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  • deramp5113
    Dec 14, 2013
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      I have not seen a source listing for AltairDOS, but I have disassembled sections of it in the past.

      After answering "Y" to interrupts, AltairDOS writes to the 2SIO/6850 to enable receive interrupts. Check your emulation of the 6850 for these steps since these haven't been tested fully when running AltairDOS without interrupts.

      If the emulated 6850 1) receives a character, and 2) has receive interrupts enabled, and 3) the 8080 has interrupts enabled, then the next M1 cycle (instruction fetch) should disable interrupts and execute a RST7 instruction instead of fetching the instruction at the PC. That should be just about all there is to it. AltairDOS should just work then.


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