Time left $60$:$57$:$29$

Which of the following is $($are$)$ illegal? Select all that apply.

Select one or more:

a$.$ LDI R$27,0$xF$5$

b$.$ LDI R$42,$ $$25$

c$.$ LDIR$16,$ $$255$

d$.$ LDIR$1,00$

e$.$ LDI R$23,50$

f$.$ LDI R$20,-128$