[Coco] OS-9 loading NEW WAY - J&R Banker 128/256k

[Robert Gault]

Bruce W. Calkins wrote:
> ----- Original Message ----- From: "Joe Grubbs"
>>
>>> > - Do a 6809 Coco2 NOS9 that took advantage of that 128k mod people have >
>>> been talking about. (I'd fund creating a board/kit if I had the money)
>>>
>>> Would probably make more sense to use the extra 64K as a RAM disk in NOS9 L1,
>>> but yeah, would be cool.
>>>
>> That is a good idea. When I do this mod to my CoCo2, I might try my hand at
>> writing the code necessary to enable this as a ram disk.
>>
> =====================
> I have an original 256k  J&B Banker in a CoCo 1.  One problem with it, and I
> assume it is a problem with the 128k version too, is that the OS-9 Boot file
> needs to be modified.  The NITROS9 boot simply does not work.  Someone will need
> to hack into the OS-9 code, figure out what the modification is and intigrate it
> into the NITROS9 boot.  The J&R Banker kit came with a program that you ran on
> your backup OS-9 boot disk and changed a couple bytes on the disk, but I have
> not figured out what module is affected, nor how.
> Bruce W.
>
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There is a detailed article in "Hot CoCo", Sept, 1985, p28-31. Memory and Video 
is selected by PEEKing addresses from $FFC0-$FFDF. There is little 
correspondence with either the SAM or GIME hardware settings. That would make 
the use of the J&R Banker with any version of OS-9 very difficult.

I'd guess that at the very least, the kernel would need to be rewritten as it 
controls memory. Also all the video drivers would need rewriting to accommodate 
video bank selection.

Robert