diff --git a/Cargo.lock b/Cargo.lock
index f03afcb..65ea43b 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -216,6 +216,7 @@ version = "0.1.0"
 dependencies = [
  "crsn",
  "libc",
+ "log",
 ]
 
 [[package]]
@@ -366,22 +367,6 @@ dependencies = [
  "thiserror",
 ]
 
-[[package]]
-name = "launcher_nox"
-version = "0.1.0"
-dependencies = [
- "anyhow",
- "clappconfig",
- "crsn",
- "crsn_arith",
- "crsn_buf",
- "crsn_stdio",
- "log",
- "serde",
- "simple_logger",
- "thiserror",
-]
-
 [[package]]
 name = "lazy_static"
 version = "1.4.0"
diff --git a/Cargo.toml b/Cargo.toml
index 31d54f3..1f66ba0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [workspace]
 members = [
     "launcher",
-    "launcher_nox",
+    #"launcher_nox",
     "crsn",
     "crsn_arith",
     "crsn_screen",
diff --git a/README.md b/README.md
index bc4ee51..fbc4ec9 100644
--- a/README.md
+++ b/README.md
@@ -738,7 +738,7 @@ To delete a buffer, use the `del` instruction - `(del @Obj)`
 
 This module uses the minifb rust crate to provide a framebuffer with key and mouse input.
 
-Colors use the `RRGGBB` hex format.
+Colors use the `0xRRGGBB` or `#RRGGBB` hex format.
 
 If input events are required, then make sure to periodically call `(sc-blit)` or `(sc-poll)`.
 This may not be needed if the auto-blit function is enabled and the display is regularly written.
@@ -753,17 +753,17 @@ such as animations.
 ; Initialize the screen (opens a window)
 (sc-init WIDTH HEIGHT)
 
-; Erase the screen (fill with black)
-(sc-erase)
-; Fill with a custom color
-(sc-erase 0xFF00FF)
-
 ; Set pixel color
-(sc-px X Y COLOR)
+(sc-wr Rd'x Rd'y Rd'color) ; legacy name: sc-px
+
+; Get pixel color
+(sc-rd Wr'color Rd'x Rd'y)
 
 ; Set screen option. Constants are pre-defined.
-; SCREEN_AUTO_BLIT (1) ... auto-blit (blit automatically on pixel write when needed to achieve the target FPS)
-; SCREEN_FPS (2) ... frame rate
+; - SCREEN_AUTO_BLIT (1) ... auto-blit (blit automatically on pixel write when needed to achieve the target FPS)
+; - SCREEN_FPS (2) ......... frame rate
+; - SCREEN_UPSCALE (3) ..... upscaling factor (big pixels). 
+;     Scales coordinates for mouse and pixels and increases pixel area
 (sc-opt OPTION VALUE)
 
 ; Blit (render the pixel buffer).
@@ -781,11 +781,24 @@ such as animations.
 
 ; Check key status. Keys are 0-127. Reads 1 if the key is pressed, 0 if not.
 ; A list of supported keys can be found in the extension source code.
-(sc-key PRESSED KEY)
+(sc-key Wr'pressed Rd'num)
 
-; Check mouse button state
+; Check mouse button state. 
 ; 0-left, 1-right, 2-middle
-(sc-mbtn PRESSED BTN)
+(sc-mbtn Wr'pressed Rd'btn)
+```
+
+### Graphic acceleration commands
+
+```
+; Fill a rectangle
+(sc-rect Rd'x Rd'y Rd'w Rd'h Rd'color)
+
+; Erase the screen (fill with black)
+(sc-erase)
+
+; Fill with a custom color
+(sc-erase Rd'color)
 ```
 
 ## Stdio module
diff --git a/crsn/src/asm/parse/arg_parser.rs b/crsn/src/asm/parse/arg_parser.rs
index e1ba4a1..0177ad1 100644
--- a/crsn/src/asm/parse/arg_parser.rs
+++ b/crsn/src/asm/parse/arg_parser.rs
@@ -45,8 +45,12 @@ impl<'a> TokenParser<'a> {
     /// Get error if not empty.
     /// The argument is substituted into the phrase "Instruction needs ...!" - i.e. "one Wr argument and a list or string"
     pub fn ensure_empty(&self, what_arguments : &str) -> Result<(), CrsnError> {
+        self.ensure_empty_custom(&format!("Instruction needs {}!", what_arguments))
+    }
+
+    pub fn ensure_empty_custom(&self, msg : &str) -> Result<(), CrsnError> {
         if self.have_more() {
-            Err(CrsnError::Parse(format!("Instruction needs {}!", what_arguments).into(), self.start_pos.clone()))
+            Err(CrsnError::Parse(msg.to_string().into(), self.start_pos.clone()))
         } else {
             Ok(())
         }
diff --git a/crsn/src/runtime/run_thread/state.rs b/crsn/src/runtime/run_thread/state.rs
index 7e0f9a4..1315ea5 100644
--- a/crsn/src/runtime/run_thread/state.rs
+++ b/crsn/src/runtime/run_thread/state.rs
@@ -115,10 +115,12 @@ impl RunState {
     }
 
     /// Read a `Rd` value
+    #[inline]
     pub fn read(&mut self, rd: impl Into<Rd>) -> Result<Value, Fault> {
         let rd = rd.into();
         // TODO dedupe
         match rd.0 {
+            RdData::Immediate(v) => Ok(v),
             RdData::Register(Register::Gen(rn)) => {
                 if likely(rn < REG_COUNT as u8) {
                     trace!("Rd {:?} = {}", rd, self.frame.gen[rn as usize]);
@@ -135,7 +137,6 @@ impl RunState {
                     Err(Fault::RegisterNotExist { reg: Register::Global(rn) })
                 }
             }
-            RdData::Immediate(v) => Ok(v),
             RdData::Register(Register::Arg(rn)) => {
                 if likely(rn < REG_COUNT as u8) {
                     trace!("Rd {:?} = {}", rd, self.frame.arg[rn as usize]);
diff --git a/crsn_screen/src/defs.rs b/crsn_screen/src/defs.rs
index 87c1d7d..cb7cb7e 100644
--- a/crsn_screen/src/defs.rs
+++ b/crsn_screen/src/defs.rs
@@ -12,6 +12,11 @@ pub enum ScreenOp {
         y: Rd,
         color: Rd,
     },
+    GetPixel {
+        color: Wr,
+        x: Rd,
+        y: Rd,
+    },
     GetMouse {
         x: Wr,
         y: Wr,
@@ -28,6 +33,13 @@ pub enum ScreenOp {
     Erase {
         color: Rd,
     },
+    FillRect {
+        x: Rd,
+        y: Rd,
+        w: Rd,
+        h: Rd,
+        color: Rd,
+    },
     Blit {
         force: Rd,
     },
diff --git a/crsn_screen/src/exec.rs b/crsn_screen/src/exec.rs
index 855d0f0..b8cb7cb 100644
--- a/crsn_screen/src/exec.rs
+++ b/crsn_screen/src/exec.rs
@@ -3,7 +3,9 @@ use std::time::{Duration, Instant};
 
 use minifb::{Key, MouseButton, MouseMode, ScaleMode, Window, WindowOptions};
 
-use crsn::asm::data::literal::Value;
+use crsn::asm::data::literal::{Value, is_negative};
+use crsn::asm::error::CrsnError;
+use crsn::asm::instr::cond::Flag;
 use crsn::module::{EvalRes, OpTrait};
 use crsn::runtime::fault::Fault;
 use crsn::runtime::run_thread::{state::RunState, ThreadInfo};
@@ -12,18 +14,21 @@ use crsn::sexp::Sexp;
 use crsn::utils::A;
 
 use crate::defs::ScreenOp;
-use crsn::asm::instr::cond::Flag;
+use std::mem;
 
 #[derive(Debug)]
 struct Opts {
     auto_blit: bool,
     frame_rate: Duration,
+    upscale: Value,
 }
 
 #[derive(Debug)]
 struct Backend {
-    width: usize,
-    height: usize,
+    width: Value,
+    height: Value,
+    log_width: Value,
+    log_height: Value,
     buffer: Vec<u32>,
     window: Option<Window>,
     last_render: Instant,
@@ -35,19 +40,33 @@ impl Default for Backend {
         Self {
             width: 0,
             height: 0,
+            log_width: 0,
+            log_height: 0,
             buffer: vec![],
             window: None,
             last_render: Instant::now().sub(Duration::from_secs(1)),
             opts: Opts {
                 auto_blit: true,
+                upscale: 1,
                 frame_rate: Duration::from_micros(16600),
             },
         }
     }
 }
 
+impl Backend {
+    pub fn draw_rect_log(&mut self, mut x: Value, mut y: Value, w: Value, h: Value, color: u32) {
+        for yy in (y * self.opts.upscale)..((y + h) * self.opts.upscale).min(self.height) {
+            for xx in (x * self.opts.upscale)..((x + w) * self.opts.upscale).min(self.width) {
+                self.buffer[(yy * self.width + xx) as usize] = color as u32;
+            }
+        }
+    }
+}
+
 pub const OPT_AUTO_BLIT: u64 = 1;
 pub const OPT_FRAME_RATE: u64 = 2;
+pub const OPT_UPSCALE: u64 = 3;
 
 // Hack for Window
 unsafe impl std::marker::Send for Backend {}
@@ -81,8 +100,22 @@ impl OpTrait for ScreenOp {
                         debug!("Set auto blit to {:?}", backend.opts.auto_blit);
                     }
                     OPT_FRAME_RATE => {
-                        backend.opts.frame_rate = Duration::from_micros(1_000_000 as u64 / val);
-                        debug!("Set frame rate to {:?}", backend.opts.frame_rate);
+                        if val == 0 {
+                            state.set_flag(Flag::Invalid, true);
+                        } else {
+                            backend.opts.frame_rate = Duration::from_micros(1_000_000 as u64 / val);
+                            debug!("Set frame rate to {:?}", backend.opts.frame_rate);
+                        }
+                    }
+                    OPT_UPSCALE => {
+                        if val == 0 {
+                            state.set_flag(Flag::Invalid, true);
+                        } else {
+                            backend.opts.upscale = val;
+                            backend.log_width = backend.width / val;
+                            backend.log_height = backend.height / val;
+                            debug!("Set upscale to {:?}", val);
+                        }
                     }
                     _other => {
                         unreachable!()
@@ -106,8 +139,9 @@ impl OpTrait for ScreenOp {
                 match &mut backend.window {
                     Some(w) => {
                         if !w.is_open() {
-                            // TODO...
-                            std::process::exit(0);
+                            debug!("Window is closed");
+                            let _ = backend.window.take();
+                            return Err(Fault::Halt);
                         }
 
                         w.update();
@@ -126,23 +160,46 @@ impl OpTrait for ScreenOp {
 
                 let backend: &mut Backend = state.ext_mut();
 
-                if x >= backend.width as u64 || y >= backend.height as u64 {
+                if x >= backend.log_width as u64 || y >= backend.log_height as u64 {
+                    state.set_flag(Flag::Overflow, true);
+                    return Ok(eres);
+                }
+
+                match &mut backend.window {
+                    Some(_w) => {
+                        backend.draw_rect_log(x, y, 1, 1, color as u32);
+                        if backend.opts.auto_blit {
+                            blit_maybe(backend)?;
+                        }
+                    }
+                    None => {
+                        state.set_flag(Flag::Invalid, true);
+                    }
+                }
+            }
+
+            ScreenOp::GetPixel { color, x, y } => {
+                state.clear_status();
+                let x = state.read(x)?;
+                let y = state.read(y)?;
+
+                let backend: &mut Backend = state.ext_mut();
+
+                if x >= backend.log_width as u64 || y >= backend.log_height as u64 {
                     state.set_flag(Flag::Overflow, true);
                     return Ok(eres);
                 }
 
                 match &mut backend.window {
                     Some(_w) => {
-                        let index = y * backend.width as u64 + x;
+                        let index = y * backend.opts.upscale * backend.width as u64 + x * backend.opts.upscale;
                         if index as usize > backend.buffer.len() {
                             warn!("Screen set pixel out of bounds");
                             state.set_flag(Flag::Invalid, true);
                         } else {
-                            backend.buffer[index as usize] = color as u32;
-
-                            if backend.opts.auto_blit {
-                                blit_maybe(backend)?;
-                            }
+                            let c = backend.buffer[index as usize];
+                            trace!("index {}, c {}", index, c);
+                            state.write(color, c as Value)?;
                         }
                     }
                     None => {
@@ -163,8 +220,11 @@ impl OpTrait for ScreenOp {
                                 state.set_flag(Flag::Overflow, true);
                             }
                             Some((xf, yf)) => {
-                                let xval = xf.round() as u64;
-                                let yval = yf.round() as u64;
+                                let mut xval = xf.round() as u64;
+                                let mut yval = yf.round() as u64;
+
+                                xval /= backend.opts.upscale;
+                                yval /= backend.opts.upscale;
 
                                 state.write(x, xval)?;
                                 state.write(y, yval)?;
@@ -227,6 +287,51 @@ impl OpTrait for ScreenOp {
                     }
                 }
             }
+            ScreenOp::FillRect {
+                x, y,
+                w, h,
+                color
+            } => {
+                let mut x = state.read(x)?;
+                let mut y = state.read(y)?;
+                let mut w = state.read(w)?;
+                let mut h = state.read(h)?;
+                let c = state.read(color)?;
+                let backend: &mut Backend = state.ext_mut();
+
+                if is_negative(w) || is_negative(h) {
+                    state.set_flag(Flag::Invalid, true);
+                    return Ok(eres);
+                }
+                if w > backend.log_width {
+                    w = backend.log_width;
+                }
+                if h > backend.log_height {
+                    h = backend.log_height;
+                }
+
+                if is_negative(x) {
+                    let xi : i64 = unsafe { mem::transmute(x) };
+                    let minus = xi.abs() as u64;
+                    w -= minus;
+                    x = 0;
+                }
+                if is_negative(y) {
+                    let yi : i64 = unsafe { mem::transmute(y) };
+                    let minus = yi.abs() as u64;
+                    h -= minus;
+                    y = 0;
+                }
+
+                match &mut backend.window {
+                    Some(_w) => {
+                        backend.draw_rect_log(x, y, w, h, c as u32);
+                    }
+                    None => {
+                        state.set_flag(Flag::Invalid, true);
+                    }
+                }
+            }
         }
 
         Ok(eres)
@@ -236,13 +341,17 @@ impl OpTrait for ScreenOp {
         match self {
             ScreenOp::SetOpt { opt, val } => sexp::list(&[A("sc-opt"), A(opt), A(val)]),
             ScreenOp::ScreenInit { width, height } => sexp::list(&[A("sc-init"), A(width), A(height)]),
-            ScreenOp::SetPixel { x, y, color } => sexp::list(&[A("sc-px"), A(x), A(y), A(color)]),
+            ScreenOp::SetPixel { x, y, color } => sexp::list(&[A("sc-wr"), A(x), A(y), A(color)]),
+            ScreenOp::GetPixel { color, x, y } => sexp::list(&[A("sc-rd"), A(color), A(x), A(y)]),
             ScreenOp::Blit { force } => sexp::list(&[A("sc-blit"), A(force)]),
             ScreenOp::Update => sexp::list(&[A("sc-poll")]),
             ScreenOp::GetMouse { x, y } => sexp::list(&[A("sc-mouse"), A(x), A(y)]),
             ScreenOp::TestKey { pressed, code } => sexp::list(&[A("sc-key"), A(pressed), A(code)]),
             ScreenOp::TestMouse { pressed, button } => sexp::list(&[A("sc-mbtn"), A(pressed), A(button)]),
             ScreenOp::Erase { color } => sexp::list(&[A("sc-erase"), A(color)]),
+            ScreenOp::FillRect { x, y, w, h, color } => {
+                sexp::list(&[A("sc-rect"), A(x), A(y), A(w), A(h), A(color)])
+            }
         }
     }
 }
@@ -266,8 +375,10 @@ fn init(state: &mut RunState, width: Value, height: Value) -> Result<(), Fault>
         return Err(Fault::NotAllowed("Screen already initialized".into()));
     }
 
-    backend.width = width as usize;
-    backend.height = height as usize;
+    backend.width = width;
+    backend.height = height;
+    backend.log_width = width;
+    backend.log_height = height;
     backend.buffer = vec![0; (width * height) as usize];
 
     backend.window = Some(window);
@@ -289,10 +400,12 @@ fn blit(backend: &mut Backend) -> Result<(), Fault> {
     let w = backend.window.as_mut().unwrap();
 
     if !w.is_open() {
+        debug!("Window is closed");
+        let _ = backend.window.take();
         return Err(Fault::Halt);
     }
 
-    w.update_with_buffer(&backend.buffer, backend.width, backend.height)
+    w.update_with_buffer(&backend.buffer, backend.width as usize, backend.height as usize)
         .expect("Update screen"); // TODO fault
 
     backend.last_render = Instant::now();
diff --git a/crsn_screen/src/lib.rs b/crsn_screen/src/lib.rs
index e87b6e7..c95e975 100644
--- a/crsn_screen/src/lib.rs
+++ b/crsn_screen/src/lib.rs
@@ -7,7 +7,7 @@ use crsn::asm::parse::arg_parser::TokenParser;
 use crsn::module::{CrsnExtension, ParseRes};
 use crsn::sexp::SourcePosition;
 use crsn::asm::data::literal::Value;
-use crate::exec::{OPT_AUTO_BLIT, OPT_FRAME_RATE};
+use crate::exec::{OPT_AUTO_BLIT, OPT_FRAME_RATE, OPT_UPSCALE};
 
 mod defs;
 mod parse;
@@ -38,6 +38,7 @@ impl CrsnExtension for ScreenOps {
         match name {
             "SCREEN_AUTO_BLIT" => Some(OPT_AUTO_BLIT),
             "SCREEN_FPS" => Some(OPT_FRAME_RATE),
+            "SCREEN_UPSCALE" => Some(OPT_UPSCALE),
             _ => None
         }
     }
diff --git a/crsn_screen/src/parse.rs b/crsn_screen/src/parse.rs
index 9f6fb78..79f3975 100644
--- a/crsn_screen/src/parse.rs
+++ b/crsn_screen/src/parse.rs
@@ -9,9 +9,10 @@ use crate::defs::ScreenOp;
 
 use super::exec::OPT_AUTO_BLIT;
 use super::exec::OPT_FRAME_RATE;
+use super::exec::OPT_UPSCALE;
 
 pub(crate) fn parse<'a>(_pos: &SourcePosition, keyword: &str, mut args: TokenParser<'a>) -> Result<ParseRes<'a, OpKind>, CrsnError> {
-    Ok(ParseRes::ext(match keyword {
+    let rv = Ok(ParseRes::ext(match keyword {
         "sc-init" => {
             ScreenOp::ScreenInit {
                 width: args.next_rd()?,
@@ -29,7 +30,7 @@ pub(crate) fn parse<'a>(_pos: &SourcePosition, keyword: &str, mut args: TokenPar
             }
         }
 
-        "sc-px" => {
+        "sc-wr" | "sc-px" => {
             ScreenOp::SetPixel {
                 x: args.next_rd()?,
                 y: args.next_rd()?,
@@ -37,6 +38,14 @@ pub(crate) fn parse<'a>(_pos: &SourcePosition, keyword: &str, mut args: TokenPar
             }
         }
 
+        "sc-rd" => {
+            ScreenOp::GetPixel {
+                color: args.next_wr()?,
+                x: args.next_rd()?,
+                y: args.next_rd()?,
+            }
+        }
+
         "sc-opt" => {
             let (val, valopt) = args.next_value()?;
             ScreenOp::SetOpt {
@@ -47,6 +56,9 @@ pub(crate) fn parse<'a>(_pos: &SourcePosition, keyword: &str, mut args: TokenPar
                     OPT_FRAME_RATE => {
                         OPT_FRAME_RATE
                     }
+                    OPT_UPSCALE => {
+                        OPT_UPSCALE
+                    }
                     _ => {
                         return Err(CrsnError::Parse("Bad screen option".into(), valopt));
                     }
@@ -90,8 +102,20 @@ pub(crate) fn parse<'a>(_pos: &SourcePosition, keyword: &str, mut args: TokenPar
             }
         }
 
+        "sc-rect" => {
+            ScreenOp::FillRect {
+                x: args.next_rd()?,
+                y: args.next_rd()?,
+                w: args.next_rd()?,
+                h: args.next_rd()?,
+                color: args.next_rd()?
+            }
+        }
+
         _other => {
             return Ok(ParseRes::Unknown(args));
         }
-    }))
+    }));
+    args.ensure_empty_custom("Too many arguments for this instruction!")?;
+    return rv;
 }
diff --git a/crsn_stdio/Cargo.toml b/crsn_stdio/Cargo.toml
index fa7469e..5a0d428 100644
--- a/crsn_stdio/Cargo.toml
+++ b/crsn_stdio/Cargo.toml
@@ -9,3 +9,4 @@ edition = "2018"
 [dependencies]
 crsn = { path = "../crsn" }
 libc = "0.2.79"
+log = "0.4.11"
diff --git a/crsn_stdio/src/lib.rs b/crsn_stdio/src/lib.rs
index 5088df4..126cec4 100644
--- a/crsn_stdio/src/lib.rs
+++ b/crsn_stdio/src/lib.rs
@@ -1,3 +1,6 @@
+#[macro_use]
+extern crate log;
+
 use crsn::asm::data::literal::Value;
 use crsn::asm::error::CrsnError;
 use crsn::asm::instr::op::OpKind;
@@ -134,6 +137,7 @@ impl StdioOps {
 
 impl Drop for StdioOps {
     fn drop(&mut self) {
+        debug!("stdin restore");
         // Un-break the terminal
         if let Some(tio) = self.old_tio.take() {
             let _ = unsafe { libc::tcsetattr(libc::STDIN_FILENO, libc::TCSANOW, &tio) };
diff --git a/examples/screen_pick_color.csn b/examples/screen_pick_color.csn
new file mode 100644
index 0000000..843992d
--- /dev/null
+++ b/examples/screen_pick_color.csn
@@ -0,0 +1,28 @@
+(
+    (sc-init 512 512)
+    (sc-opt SCREEN_UPSCALE 16)
+    (def W 32)
+
+    (lds @cout "Drag colors to draw...\n")
+
+    (sc-wr 0 0 #ff00ff)
+    (sc-wr 5 5 #ffff00)
+    (sc-wr 15 15 #00ff00)
+    (sc-blit)
+
+    (:l)
+        (sc-poll)
+        (sc-mbtn r0 0)
+        (j.z :nope)
+
+        (sc-mouse r0 r1)
+        (sc-rd r3 r0 r1)
+        (sub r0 1)
+        (sub r1 1)
+        (sc-rect r0 r1 3 3 r3)
+        (sc-blit)
+
+        (:nope)
+        (mslp 10)
+    (j :l)
+)
diff --git a/examples/screen_upscale.csn b/examples/screen_upscale.csn
new file mode 100644
index 0000000..1fcc2e8
--- /dev/null
+++ b/examples/screen_upscale.csn
@@ -0,0 +1,14 @@
+(
+    (sc-init 512 512)
+    (sc-opt SCREEN_UPSCALE 32)
+
+    (sc-wr 0 0 #ff00ff)
+    (sc-wr 1 1 #ffff00)
+    (sc-wr 15 15 #00ff00)
+    (sc-blit)
+
+    (:l)
+        (sc-poll)
+        (mslp 100)
+    (j :l)
+)
diff --git a/examples/screen_upscale_mouse.csn b/examples/screen_upscale_mouse.csn
new file mode 100644
index 0000000..aeec7d9
--- /dev/null
+++ b/examples/screen_upscale_mouse.csn
@@ -0,0 +1,15 @@
+(
+    (sc-init 512 512)
+    (sc-opt SCREEN_UPSCALE 16)
+    (def W 32)
+
+    (:l)
+        (sc-poll)
+        (sc-erase)
+        (sc-mouse r0 r1)
+        (sc-rect 0 r1 W 1 #ff0000)
+        (sc-rect r0 0 1 W #0066ff)
+        (sc-wr r0 r1 #ffffff)
+        (mslp 10)
+    (j :l)
+)