The "Macintosh LC Computer Developer Note" is wrong.
The memory spaced used by VRAM is in the following ranges:
24-bit mode 32-bit mode
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$F4 0000 to $FB FFFF $50F4 0000 to $50FB FFFF
With the 512K VRAM SIMM installed, the entire range from $F4 0000 to $FB
FFFF (24-bit mode) or $50F4 0000 to $50FB FFFF (32-bit mode) is used. ($FB
FFFF minus $F4 0000 is $07 FFFF, which equals 512K.)
With the 256K VRAM SIMM installed, the range from $F4 0000 to $F7 FFFF
(24-bit mode) or $50F4 0000 to $50F7 FFFF (32-bit mode) is used; $FB FFFF
minus $F7 0000 is $03 FFFF, which equals 128K.
Note: The range from $F8 0000 to $FB FFFF (24-bit mode) or $50F8 0000 to
$50FB FFFF (32-bit mode) maps to the range from $F4 0000 to $F7 FFFF
(24-bit mode) or $50F4 0000 to $50F7 FFFF (32-bit mode). In other words,
if a change is made to $F8 0000, the same change will be made to $F4 0000.
The reverse holds true as well: a change to $F4 0000 will reflect in $F8
0000.