[Coco] CoCo 3 MMU test for all
diegoba at adinet.com.uy
Sun Jan 20 12:55:10 EST 2008
I just tried with a '86 GIME and 128 Kb, also getting 121.
Joel Ewy 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
>> At the stock WIDTH 32 prompt, type:
>> 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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