SY_Turbo will change the init value of 1 and therefore fkhfm.
No it wont.
In the FR and in code the initialisation value is locked to 1.00.
SY_TURBO has no control over fkhfm in ANY condition. It simply changes what fkhfm is multiplied by.
If SY_TURBO is true then mshfm_w = (fkhfm * 1) * (mlhfmm_w - MLOFS)
If SY_TURBO is false then mshfm_w = (fkhfm * Fkup) * (mlhfmm_w - MLOFS)
In this case SY_TURBO is true, so in short and in code we have:
mshfm_w = fkhfm * (mlhfmm_w - MLOFS)
SY_TURBO changes how fkhfm is used, but NOT its contents.
SY_TURBO is a compile time option, and as it is set in the file in question, any code to do with fpuk is simply not there.
Here is the initialisation of fkhfm(byte_8A0C) being set to 1.00 (0x80)
sub_6846C:
6846C movb rl4, #80h
68470 movb byte_8A0C, rl4
68474 rets
Here is fkhfm(byte_8A0C) being filled with the contents of KFKHFM (0x10DA0), yo can also see a 16 bit equivalent(word_9F72) value is also created.
sub_68476:
68476 mov r12, #0DA0h
6847A movbz r13, byte_F89C
6847E movbz r14, byte_F9B5
68482 calls 0, sub_7312
68486 movb byte_8A0C, rl4
6848A movbz r4, rl4
6848C shl r4, #7
6848E mov word_9F72, r4
68492 rets
This is the ONLY 2 places in code(original file) that byte_8A0C is written to.