pub fn pull(&mut self) -> u8 {
        let sp = self.sp as u16;
        self.sp += 1;
        self.read(0x100 + sp)
    }
// pull a value from the stack
pull a value from the stack
pull a value from the stack
pub fn pull(&mut self) -> u8 {
        let sp = self.sp as u16;
        self.sp += 1;
        self.read(0x100 + sp)
    }
pub fn pull ( & mut self ) -> u8 { let sp = self . sp as u16 ; self . sp += 1 ; self . read ( 0x100 + sp ) }
pull a value from the stack
pull a value from the stack
&mut self