Re: A86: Asm-86 12k cap

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Re: A86: Asm-86 12k cap



>Can a RAM page be put out port 5?  I know that a ROM page can be put out
port 6.
>


According to Alan Bailey 86ports.txt, you can.

Port 5 - Page change at $4000 - $7FFF
Port 6 - Page change at $8000 - $BFFF

And you can load ram pages in both!

It the ram pages are the same, then $4000 would also be mapped as $8000 and
if you modified $4000, it would modify $8000 (which are the same web page
anyway)

But who cares about that. You could have linear memory basically, with Page
1 at $4000 and have 12k to play with and another page at $8000. What other
page of memory do we have to play with? Ram Page 2? You would have to have
another program written asm full of junk taking up around 16K (if thats
legal, it wont be going into ram Page 0 though, so why not?). Then you would
have to copy 16K from Ram Page 2, use _FINDSYM and bunch of abs addresses to
temporarily store it in the asm file, and then the ram would be free (I
guess?) and just copy that 16K from the asm program that was took off of Ram
Page 2 and put it back... If you starting $8000 though you are already
killing the floating point stack, I dont see why temporarily moving the
operator stack would hurt anything. Unless one of the interrupt programs use
the operator stack.. Disable interrupts!

-Matt
http://www.dogtech.com/cybop/ti86/

>If you put the first 12k out port five, you could add another 16k using
port 6.
>The only
>problem is that the ROM call emulation would probably have to be changed
(not
>having
>page $0d), but since you would have to check for ROM versions, you could
use
>that
>call on page 0 that swaps the page back after it's finished or just use the
>calls on page
>0.  Who knows? ... that might even get it to emulate faster.
>
>Kirk Meyer wrote:
>
>> that's not possible.  the way 85 programs are simulated is an 85-like
>> environment is created from $8000-$BFFF in the 86 memory on RAM page 1,
>> which can be used for this purpose.  since program execution on an 85
starts
>> at about $9000 (or even later), this leaves only 12K of RAM page 1 to be
>> used by programs.  you cannot use beyond the $BFFF address because $C000
is
>> used by _getky routines and even if you move that data somewhere else
>> temporarily, lots of things would be corrupted (if you didn't understand
>> that sentence, that's good, 'cause neither did I :)
>>
>>     Kirk
>>
>> Lifoo wrote:
>>
>> > Does anyone know of a shell of prog that removes the 12k CAPof progs.
>> > There are many games for the 85 and 83 that won't run on the 86 because
>> > they are too large.  If there isn't a prog like that.  Then I think
that
>> > that would be a good idea.
>
>
>
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