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cardiograph-computer/notes/2023-08-15--dev-notes.md

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Dev notes — 2023-08-15

Goals for today

  • Review planned changes to simulator

    • 'opcodes' and 'operands'
    • fix $00 contains $20 bug

  • Review planned changes to the system

    • CHP, CFC -> FHP, FTG -- dev note 2023-08-07
    • ? 5x5 display
    • bank-switching flag in 0 page

  • Implement any changes necessary for writing a program?

  • Write a program

    • LOGO turtle on 5x5?

Overflow flag

Ken Shirriff, The 6502 overflow flag explained mathematically:

A common definition of overflow is V = C6 xor C7. That is, overflow happens if the carry into bit 7 is different from the carry out.