How to set a second bit of the register ?

[littlefield]

A small computer has an 8 bit CPU and only one register.
XOR - is the only assembly command it understands.
How to set a second bit of the register ?
The initial state of the register is unknown.

 

[vlsi_freak]

Hi.

I did not clearly understand your question. As far as i understood, u can write a value to the register if you know the address of that register.

If the initial value of the register is '0' u can use the instr

XOR BIT, '1';

Hope it helps.

Thanks

 

[stevepre]

do you need to keep other bits same as their original value? Or it is OK to clear them to 0?

 

[asicganesh]

You can do this by using the following two steps:

XOR BIT, BIT; --> will reset the bit
XOR BIT, '1'; --> will set the bit

Hope this works!!

Regards
Ganesh S

 

[hamed_sotoudi]

if u want to have the other bits unchanged it is imposible. u need at least to register to do this. but the other bits is not important for u do like this:
(a is your register)
a= a xor a
a = a xor 04h