[Coco] Hi! I'm new here!

[Hugo Dufort]

I want to enable the hi-res modes in Basic using only pokes. I'm pretty 
sure I've done that in the past.

I tried the following naive sequence:
poke &hFF98,192(bit7=1 for graphics, bit6=1 for mmu)
poke &hFF99,30 (select 320x200x16 using bit mask)
poke &hFF90,0 (b7=0 for high-res)

Is it necessary to tell the MMU where to map the graphics array?

Since I don't have all bit mask defs, I'm pretty sure I'm breaking 
things in memory.

Hugo

Le 2015-03-01 21:05, Robert Gault a écrit :
> Hugo Dufort wrote:
>
>> <snip>
>> Reading the documentation, I can't even figure out how to initialize
>> the high-res graphics. I would like to first test the functionalities 
>> in Basic
>> (init graphics using pokes/peeks, vertical/horizontal scrolling, 
>> memory copy, etc.)
>>
>> Right now I'm trying to figure out the high-res graphics using memory 
>> addresses
>> FF90 to FF9F. I also want to understand how to set & move the graphic 
>> port
>> adress in memory (MMU banks?) I'd go with 256x200x16 and try the 
>> scrolling
>> pokes. By the way, is anyone using the 320x225 or 256x225 modes? Are 
>> they
>> useful? Thanks.
>>
>> Hugo
>>
>
> Greetings and I hope you enjoy this listserver!
>
> To turn on the Coco3 hi-res screens from Basic, there are two simple 
> methods. The easiest uses the hi-res text screens which can be turned 
> on with a command.
> WIDTH40    you get a 40 column text screen
> WIDTH80    you get an 80 column text screen
>
> You can turn on the hi-res graphic screens with simple commands but 
> they will not stay turned on unless a program is running. HSCREEN 
> mode   is the command needed. The modes are
> mode          screen type
> 0               revert to low-res PMODE
> 1               320x192,  4 color
> 2               320x192, 16 color
> 3               640x192,  2 color
> 4               640x192,  4 color
>
> You can't arbitrarily alter the formats of these screens as they will 
> be reset by Basic. However, you can make changes within ml programs or 
> you can patch Basic to force changes in the screen formats.
> All Coco3 units run in full RAM mode, that means you can POKE changes 
> to the ROM code. You will want to find the Coco3 Service Manual and 
> the "Unravelled" series of books on-line for complete discussions and 
> listing of the ROM code.
> The screen formats are controlled by two tables at
> $E032-E04C  text screens
> $E070-$E081 graphic screens
> If you change the bytes corresponding to $FF98-$FF99, then you can 
> alter the number of rows per text letter and the horizontal and 
> vertical screen size.
>
> I normally run OS-9 (NitrOS-9) with 80x225 text screens. There is not 
> much point in trying to change the Basic graphic/text screens as the 
> ROM code does not support 225 lines. If you patch the ROM code, then 
> you can use the larger screens.
> There has been some experimentation with unsupported screen settings 
> and you can find discussions at
> http://www.tandycoco.com/forum/         limited activity
> and
> http://www.coco3.com/community/         essentially inactive
>
> To understand the use of $FF90-$FF9F, you should study the Coco3 
> service manual and the code in the Unravelled series. Ask specific 
> questions and you will get answers on the listserver.
>
> Robert
>
>


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