[Coco] How does the SCS line / GIME Setting Work?

[Gene Heskett]

On Saturday 19 June 2010, jdaggett at gate.net wrote:
>Okay
>
>I am not going to argue the point anymore. I just think you are wrong. If
> not, then Kevin Darling was wrong.  I will leave it al that.
>
>james
>
James, Kevin has been wrong before, and in fact that was the reason I put on 
my bulletproof stuff and started on RBF.MN all those years ago, even before 
the 6309 was discovered.  The level2 version was not doing exactly as the 
docs said it should, so I fixed that code in 7 or 8 different locations 
before I got to Ed34 and thought I was done.  But that one had a land mine 
in its FD.SEG(48) handling that I put in :(, so now we've had 2 or 3 more 
versions since.

>On 19 Jun 2010 at 14:37, Darren A wrote:
>> On 6/19/10, jdaggett at gate.net wrote:
>> > The MC2 bit of the INIT0 ($FF90) register controls what is encoded
>> > onto the S BUSS when
>> > the MPU addresses in the range of $FF40 to $FF5F. Only a 16 bit window
>> > is active at
>> > anytime. When the MC2 bit is set then we have the standard SCS which
>> > is encoded as $011
>> > on the S BUS and then when the MPU addresses in the range of $FF40 to
>> > $FF4F then bit #6
>> > of the LS138 is asserted low.
>>
>> ---
>>
>> That is not correct.  When the MC2 bit is set, the entire 32-byte
>> range of FF40-FF5F causes bit 6 of the LS138 to go low. This matches
>> the way the SAM works.
>>
>> Darren
>>
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>
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-- 
Cheers, Gene
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