I was asked to program using Z80 simulator IDE and its assembler to,

subtract a hex number in memory location F101h from a hex number in F100h and stores the value in memory location F202h with the following meaning:
i) 01h if the result is negative;
ii) 00h if the result is zero;
iii) FFh if the result is positive

I already did the first part. Correct me if it's wrong.

ORG 0F000h
LD A, (0F100H)
LD B, A
LD A, (0F101h)
SUB A,B
LD (0F202h), A
HALT

Now, I need help with the numbered parts. Thanks.

update: ok, I tried assembling the code and found an error. The 'SUB' was not recognized as instruction. Now, I'm running out of idea. This whole thing is very new to me..