Posted By
SVS
on 2015-12-21
06:20:57
 |  Re: unused I/O location for debug purposes
I did perform some tests on a real Plus4.
The memory not used by TED, $FF20...$FF1D is free usable RAM. I mean that you can write there your values and they remain without been affected by O.S. or by TED.
On the ROM these locations are filled by $6A $00 $6A $00 ...
Referring to the RAM area from $FF40 to $FFFF it is freely available in my opinion. From what I remember I "should" have used it in my old SVS-OS for the RamDisk utility. The same addresses on the ROM show garbage with a possible text "WBUE9101" whatever it means.
Note that I have installed OS96 ROMs.
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