[Coco] CoCo 3 MMU test for all
operator at coco3.com
Sun Jan 20 13:57:11 EST 2008
I'm interested in what the GIME reports, but I'm looking for a single
cure for the MMU-LOADM (or LOADMMU ?) :) trick even if it means
writing over the code in DOS that does a readback of each byte loaded
and written to memory. This would let me do Great things with audio
and graphics by stashing them away out of the 64k address without
having to load stuff separately after the game shell loads. I want
to pack it all in one LOADM file.
At 10:16 AM 1/20/2008, you wrote:
>Roger Taylor wrote:
> > Dudes and dudettes,
> > There's a trick to creating super long LOADM'able programs on a CoCo 3
> > but it relies on every CoCo 3 giving the same results of the following
> > test:
> > At the stock WIDTH 32 prompt, type:
> > ?PEEK(65441)
> > Won't you please type the above command on your real CoCo 3 only (not
> > an emulator), and post the results here?
> > It *should* hopefully yield 57 which is an MMU block #, ofcourse. If
> > it gives a reading of 11xxxxxx where the high two bits are set (or
> > either of the 2 high bits) then a separate special LOADMable program
> > would have to be created for that CoCo variation. I could perhaps try
> > to LOADM a patch right into Disk BASIC that would ignore bad readbacks
> > while loading, but with all the types of DOSes out there, I doubt I
> > will take that route. The upper 2 bit statuses also might depend on
> > the memory upgrade installed, etc.
>I get 121 here on a CoCo 3 with a Tandy 512K upgrade. I think that on a
>stock CoCo the memory is mapped into the upper range and mirrored
>throughout the lower addresses. If you are using an emulator (which
>usually supports up to 2M) things may be different.
>1. My CoCo 3 service manual says those registers are "Write Only". Do
>they mean that in the same sense as "No User Serviceable Parts Inside"? :)
>2. I have a 1986 GIME chip laying around. Should I pop that in and see
>if it's any different?
> > I have already created a test copy of Jeweled which LOADMs the 32k
> > backdrop graphics into MMU 48-51 before loading the program itself.
> > This is nothing new, but it *is* 2008 and my way of thinking is not
> > like it was in 1985 or even 2005. In a 512k CoCo 3 using the extended
> > LOADM trick, huge extraordinary-for-a-CoCo 3 games with HQ sound
> > effects and dithered graphics could be loaded in up to the size of a
> > floppy disk, ofcourse. A 128k-size .bin file containing the entire
> > game contents? I'll soon see.
> > --
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> > Coco at maltedmedia.com
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