tx0.cpp: Further fixes

- Load typewriter input into correct bit positions of LR
- Invert MSB of display coordinates (fixes tic-tac-toe grid)
- tx0_8kw: Resolve confusion between SHR and CYR semantics (these were incorrectly swapped)

src/devices/cpu/tx0/tx0.cpp

@@ -989,12 +989,12 @@ void tx0_8kw_device::execute_instruction_8kw()
 				{
 					switch (MAR & 0000300)
 					{
-					case 0000000:   /* (1.6) CYR = CYcle ac contents Right one binary
+					case 0000200:   /* (1.6) CYR = CYcle ac contents Right one binary
 					                    position (AC(17) -> AC(0)) */
 						AC = (AC >> 1) | ((AC & 1) << 17);
 						break;
 
-					case 0000200:   /* (1.6) CYcle ac contents Right one binary
+					case 0000000:   /* (1.6) SHR = SHift ac contents Right one binary
 					                    position (AC(0) unchanged) */
 						AC = (AC >> 1) | (AC & 0400000);
 						break;

src/mame/drivers/tx0.cpp

@@ -1427,9 +1427,7 @@ void tx0_state::tx0_keyboard()
 				;
 			charcode = (i << 4) + j;
 			/* shuffle and insert data into LR */
-			/* BTW, I am not sure how the char code is combined with the
-			previous LR */
-			lr = (1 << 17) | ((charcode & 040) << 10) | ((charcode & 020) << 8) | ((charcode & 010) << 6) | ((charcode & 004) << 4) | ((charcode & 002) << 2) | ((charcode & 001) << 1);
+			lr = (1 << 17) | (charcode << 11) | m_maincpu->state_int(TX0_LR);
 			/* write modified LR */
 			m_maincpu->set_state_int(TX0_LR, lr);
 			tx0_typewriter_drawchar(charcode); /* we want to echo input */

src/mame/video/tx0.cpp

@@ -56,8 +56,8 @@ WRITE_LINE_MEMBER(tx0_state::screen_vblank_tx0)
 void tx0_state::tx0_plot(int x, int y)
 {
 	/* compute pixel coordinates and plot */
-	x = x*crt_window_width/0777;
-	y = y*crt_window_height/0777;
+	x = (x ^ 0400) * crt_window_width / 0777;
+	y = (y ^ 0400) * crt_window_height / 0777;
 	m_crt->plot(x, y);
 }