[Coco] Help with some HiRes CoCo 3 MMU settings

[Glen Hewlett]

His Robert,

Another good Interrupt thing to know.

Cheers,
Glen

> On Dec 7, 2016, at 9:13 PM, Robert Gault <robert.gault at att.net> wrote:
> 
> Glen Hewlett wrote:
>> Hi Robert,
>> 
>> Thanks for the example code, It works fine for the FIRQ as it is, and I can hopefully use this to get my IRQ version working.  I noticed that in your Interrupt section the first thing you do is a “lda $FF93” is there a reason for reading the FIRQENR every time the interrupt is called?
>> 
>> Just trying to learn…
>> 
>> Thanks again.  Your code will help.
>> Glen
> 
> I read $FF93 because I chose to use FIRQ instead of IRQ. Look at the beginning of the code where I installed FIRQ,pcr and turned on FIRQ with
> lda #%00100000
> ...
> sta $FF93
> 
> In the case of the GIME, reading $FF92 or $FF93 clears the interrupt. For cpu interrupts, you would clear the interrupt flags at $FF01, $FF03, $FF21, and $FF23; bit#7 (0-7) for each.
> 
> Robert
> 
> 
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