[Coco] CoCo 3 MMU test for all

[Mark Marlette]

Roger,

To be compatible with a 512k system when/if the end user ever updated.

Just as if you poke in values in to the MMU that would move you out 
of 512k. They are just pages of repeat lower address that 2^y as you 
go up in the address space.

Going up in memory space that logic works, going decreasing it does 
not because the upper address space is always present.

Binary thing.....hex thing. Decimal thing....I'll hit the 
delete/trash icon. Last warning. :)

Stick with hex and you will understand how it works, remember it and 
possibly see how the hardware is functioning.

Regards,

Mark
Cloud-9






At 1/20/2008 08:02 PM, you wrote:

>At 07:43 PM 1/20/2008, you wrote:
>>Roger,
>>
>>You must be still sleep deprived or you don't understand the GIME.
>
>Thanks, Mark.  :)  I'd have to lean towards me needing a nap, which 
>I just woke up from.
>
>You say $0-$f is for a 128k CoCo, so why are blocks 48-63 used 
>within BASIC?   56-63 are stored in the TASK 0 64k map.
>
>
>
>>I always thought programmers did it in hex? I know hardware designers do!
>
>I'm a decimal + hex guy, using both randomly depending on the mood 
>I'm in.   Believe me, I realize the frustration to other coders when 
>I post decimal values.  Robert Gault probably pulls his hair out 
>every time we have a technical chat.
>
>
>
>
>>Per your table below. You can't look at it that way. Bits 6/7 ARE 
>>NOT READABLE. That is why you AND out bits6/7.
>>
>>128k: 112-127  s/b 0-$0f
>>512k: 64-127   s/b 0-$3f
>>1 meg: 64-255  s/b 0-$7f
>>2 meg: 0-255   s/b 0-$ff  (only one you got right, think hex, it is easier)
>
>The table was a "maybe this is what's really happening, and not what 
>I've believed has been happening all these years".  I didn't post 
>the table as a guideline.  It was more of a question than the answer.
>
>I always use 48-63 on a 128k CoCo.  I don't read back the MMU 
>registers.  I make my own values and write only.  I realize the 
>upper 2 bits behave this way and is why I'm trying to gather more 
>information so I can pull off a LOADM trick.
>
>
>
>
>--
>Coco mailing list
>Coco at maltedmedia.com
>http://five.pairlist.net/mailman/listinfo/coco
>
>
>
>
>--
>No virus found in this incoming message.
>Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 
>269.19.7/1233 - Release Date: 1/19/2008 6:37 PM
-------------- next part --------------


No virus found in this outgoing message.
Checked by AVG Free Edition. 
Version: 7.5.516 / Virus Database: 269.19.7/1233 - Release Date: 1/19/2008 6:37 PM