Re: Double-Width HiRes

[greg@apple2.com]

In article <38313576.E5F82CB3@swbell.net>,
rubywand@swbell.net wrote:
>jonrelay@napanet.net (Jon Bettencourt) wrote:
>>rubywand@swbell.net wrote:

>>>  the Aux bank part  is in $2000-$3FFF
>>>  the Main bank part is in $4000-$5FFF.
>>>
>>> All of this is, naturally, in Main bank memory.

>> Is this how DazzleDraw pictures are stored? Or are they stored main-memory
>> part first, like I assumed in the first place? The 16K file that I want to
>> load into double hi-res is a DazzleDraw file.

>      The Aux bank part is in $2000-$3FFF and the Main bank part is in
> $4000-$5FFF. This is pretty much the standard way of storing DHR pics. (Think
> Beagle used to store the parts of the pic in separate files. That idea never
> really became popular.)
>
> Although the storage order requires an extra move if you display from 'DHR
> page 1', it requires just one move if you display from 'DHR page 2'.

So, for page 1, under ProDOS, you do the memory move using two BLOADs:

    BLOAD sixteen.k.file,A$2000,B$2000
    BLOAD sixteen.k.file,A$4000,L$2000

which gets main bank in $2000 and aux bank data in $4000, and

    BSAVE eight.k.file,A$4000,L$2000,S3,D2

Then (non-destructively) activate DHR mode page 1 and there's your picture.

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