Re: [cc65] Disable KERNAL ROM ?

From: <>
Date: 2013-02-13 14:35:44
On 2013-02-11, at 14:13, Oliver Schmidt wrote:

> Note that by this usage scenario there's no problem with code banking
> out itself as the thunks

What are "thunks" in this context?

> are of course placed in the CODE segment.
> There's no problem with data not available to the ROM as only code is
> placed in high RAM. And if there's desire for a C program to call some
> arbitrary ROM routine it can use the _sys() function which does the
> necessary banking like the thunks.
> I understand that the C64 would additionally require the setup of an
> IRQ thunk handler...

I am not 100% sure if I understand but IRQ and NMI vectors are on the top of KERNAL ROM. If this is banked out at least NMI should be covered but IRQ preferably as well. This can be done by placing appropriate values in the RAM but the values has to be "appropriate" as original ones point to ROM locations.

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Received on Wed Feb 13 14:35:56 2013

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