Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
Hi there,
There is an issue with role permissions that is being worked on at the moment.
If you are having trouble with access or permissions on regional forums please post here to get access: https://www.boards.ie/discussion/2058365403/you-do-not-have-permission-for-that#latest

Motorola 68020 SUB instruction

  • 12-12-2019 12:57pm
    #1
    funkey_monkey
    Registered Users, Registered Users 2 Posts: 8,593 ✭✭✭ 


    SUB.W R0, 0, R3

    The Carry flag is set if the operation borrowed. Essentially, what is happening here is that R3 is negated (0 - R3) and if this requires a borrow, then the Carry Flag is set for R0.

    How does this work? I can't figure out how it is set. The code using this Carry flag to determine if the least significant bit in R3 is 0 or 1.

    Thanks.


Advertisement