diff --git a/Cargo.toml b/Cargo.toml
index 19671da..8fde732 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,8 +1,9 @@
+cargo-features = ["edition2021"]
 [package]
 name = "coremem"
 version = "0.1.0"
 authors = ["Colin <colin@uninsane.org>"]
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
@@ -19,6 +20,7 @@ float_eq = "0.5"
 font8x8 = "0.2"
 image = "0.23"
 imageproc = "0.21"
+indexmap = "1.6"
 itertools = "0.9"
 lazy_static = "1.4"
 log = "0.4"
diff --git a/examples/wrapped_torus.rs b/examples/wrapped_torus.rs
index 1f7dbeb..f590a0f 100644
--- a/examples/wrapped_torus.rs
+++ b/examples/wrapped_torus.rs
@@ -36,7 +36,7 @@ fn main() {
     let size_px = Index((width_px, height_px, depth_px).into());
     let mut driver: Driver<Real> = Driver::new(size_px, feat_size);
     driver.set_steps_per_stim(10);
-    let base = "wrapped_torus-30-current-decay";
+    let base = "wrapped_torus-31-current-decay";
 
     let ferro1_center = half_width - ferro_major - 0.5*ferro_spacing;
     let ferro1_region = Torus::new_xy(Meters::new(ferro1_center, half_height, half_depth), ferro_major, ferro_minor);
@@ -126,7 +126,9 @@ fn main() {
     );
     let _ = std::fs::create_dir_all(&prefix);
 
-    driver.add_serializer_renderer(&*format!("{}/frame-", prefix), 5000);
+    driver.add_state_file(&*format!("{}/state.bc", prefix), 1000);
+    driver.add_csv_renderer(&*format!("{}/meas.csv", prefix), 200);
+    driver.add_serializer_renderer(&*format!("{}/frame-", prefix), 20000);
 
     driver.step_until(duration);
 }
diff --git a/src/driver.rs b/src/driver.rs
index 9b1e717..174cb8e 100644
--- a/src/driver.rs
+++ b/src/driver.rs
@@ -101,6 +101,10 @@ impl<R: Real, M: Material<R> + Send + Sync + 'static> Driver<R, M> {
     pub fn add_term_renderer(&mut self, step_frequency: u64) {
         self.add_renderer(render::ColorTermRenderer, "terminal", step_frequency);
     }
+
+    pub fn add_csv_renderer(&mut self, path: &str, step_frequency: u64) {
+        self.add_renderer(render::CsvRenderer::new(path), path, step_frequency);
+    }
 }
 
 impl<R: Real + Send + Sync + Serialize, M: Material<R> + Serialize + Send + Sync + 'static> Driver<R, M> {
diff --git a/src/meas.rs b/src/meas.rs
index 498bbe9..f8bd25a 100644
--- a/src/meas.rs
+++ b/src/meas.rs
@@ -1,25 +1,24 @@
 use crate::geom::{Meters, Region, Torus, Vec3, WorldRegion};
 use crate::real::{Real as _, ToFloat as _};
 use crate::sim::GenericSim;
-use common_macros::b_tree_map;
 use dyn_clone::{self, DynClone};
+use indexmap::IndexMap;
 use serde::{Serialize, Deserialize};
-use std::collections::BTreeMap;
 
 // TODO: remove this Clone and Send requirement? Have Measurements be shared by-reference across
 // threads? i.e. Sync, and no Clone
 #[typetag::serde(tag = "type")]
 pub trait AbstractMeasurement: Send + Sync + DynClone {
     fn eval(&self, state: &dyn GenericSim) -> String;
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String>;
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String>;
 }
 dyn_clone::clone_trait_object!(AbstractMeasurement);
 
-pub fn eval_multiple_kv(state: &dyn GenericSim, meas: &[Box<dyn AbstractMeasurement>]) -> BTreeMap<String, String> {
-    let mut r = BTreeMap::new();
+pub fn eval_multiple_kv(state: &dyn GenericSim, meas: &[Box<dyn AbstractMeasurement>]) -> IndexMap<String, String> {
+    let mut r = IndexMap::new();
     for m in meas {
-        let mut other = m.key_value(state);
-        r.append(&mut other);
+        let other = m.key_value(state);
+        r.extend(other.into_iter());
     }
     r
 }
@@ -32,11 +31,11 @@ impl AbstractMeasurement for Time {
     fn eval(&self, state: &dyn GenericSim) -> String {
         format!("{:.3e}s (step {})", state.time(), state.step_no())
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
-        b_tree_map! {
-            "time".to_string() => state.time().to_string(),
-            "step".to_string() => state.step_no().to_string(),
-        }
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
+        [
+            ("step".to_string(), state.step_no().to_string()),
+            ("time".to_string(), state.time().to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -48,13 +47,13 @@ impl AbstractMeasurement for Meta {
     fn eval(&self, state: &dyn GenericSim) -> String {
         format!("{}x{}x{} feat: {:.1e}m", state.width(), state.height(), state.depth(), state.feature_size())
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
-        b_tree_map! {
-            "width".to_string() => state.width().to_string(),
-            "height".to_string() => state.height().to_string(),
-            "depth".to_string() => state.depth().to_string(),
-            "feature_size".to_string() => state.feature_size().to_string(),
-        }
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
+        [
+            ("width".to_string(), state.width().to_string()),
+            ("height".to_string(), state.height().to_string()),
+            ("depth".to_string(), state.depth().to_string()),
+            ("feature_size".to_string(), state.feature_size().to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -72,10 +71,10 @@ impl AbstractMeasurement for Label {
     fn eval(&self, _state: &dyn GenericSim) -> String {
         self.0.clone()
     }
-    fn key_value(&self, _state: &dyn GenericSim) -> BTreeMap<String, String> {
-        b_tree_map! {
-            self.0.clone() => self.0.clone(),
-        }
+    fn key_value(&self, _state: &dyn GenericSim) -> IndexMap<String, String> {
+        [
+            (self.0.clone(), self.0.clone()),
+        ].into_iter().collect()
     }
 }
 
@@ -157,12 +156,12 @@ impl AbstractMeasurement for Current {
             mean_current_mag,
             mean_current_vec)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let (mean_current_mag, mean_current_vec) = self.data(state);
-        b_tree_map! {
-            format!("Imag/cell({})", self.name) => mean_current_mag.to_string(),
-            format!("I/cell({})", self.name) => mean_current_vec.to_string(),
-        }
+        [
+            (format!("Imag/cell({})", self.name), mean_current_mag.to_string()),
+            (format!("I/cell({})", self.name), mean_current_vec.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -202,11 +201,11 @@ impl AbstractMeasurement for CurrentLoop {
         let cross_sectional_current = self.data(state);
         format!("I({}): {:.2e}", self.name, cross_sectional_current)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let cross_sectional_current = self.data(state);
-        b_tree_map! {
-            format!("I({})", self.name) => cross_sectional_current.to_string(),
-        }
+        [
+            (format!("I({})", self.name), cross_sectional_current.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -276,13 +275,13 @@ impl AbstractMeasurement for MagneticLoop {
             self.name, mean_directed_h,
         )
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let (mean_directed_m, mean_directed_b, mean_directed_h) = self.data(state);
-        b_tree_map! {
-            format!("M({})", self.name) => mean_directed_m.to_string(),
-            format!("B({})", self.name) => mean_directed_b.to_string(),
-            format!("H({})", self.name) => mean_directed_h.to_string(),
-        }
+        [
+            (format!("M({})", self.name), mean_directed_m.to_string()),
+            (format!("B({})", self.name), mean_directed_b.to_string()),
+            (format!("H({})", self.name), mean_directed_h.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -317,11 +316,11 @@ impl AbstractMeasurement for MagneticFlux {
         let mean_mag = self.data(state);
         format!("Bavg({}): {:.2e}", self.name, mean_mag)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let mean_mag = self.data(state);
-        b_tree_map! {
-            format!("Bavg({})", self.name) => mean_mag.to_string(),
-        }
+        [
+            (format!("Bavg({})", self.name), mean_mag.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -356,11 +355,11 @@ impl AbstractMeasurement for Magnetization {
         let mean_mag = self.data(state);
         format!("Mavg({}): {:.2e}", self.name, mean_mag)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let mean_mag = self.data(state);
-        b_tree_map! {
-            format!("Mavg({})", self.name) => mean_mag.to_string(),
-        }
+        [
+            (format!("Mavg({})", self.name), mean_mag.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -378,11 +377,11 @@ impl AbstractMeasurement for MagnetizationAt {
         let m = state.sample(self.0).m();
         format!("M{}: {:.2e}", loc(self.0), m)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let m = state.sample(self.0).m();
-        b_tree_map! {
-            format!("M{}", loc(self.0)) => m.to_string(),
-        }
+        [
+            (format!("M{}", loc(self.0)), m.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -396,11 +395,11 @@ impl AbstractMeasurement for MagneticFluxAt {
         let b = state.sample(self.0).b();
         format!("B{}: {:.2e}", loc(self.0), b)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let b = state.sample(self.0).b();
-        b_tree_map! {
-            format!("B{}", loc(self.0)) => b.to_string(),
-        }
+        [
+            (format!("B{}", loc(self.0)), b.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -414,11 +413,11 @@ impl AbstractMeasurement for MagneticStrengthAt {
         let h = state.sample(self.0).h();
         format!("H{}: {:.2e}", loc(self.0), h)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let h = state.sample(self.0).h();
-        b_tree_map! {
-            format!("H{}", loc(self.0)) => h.to_string(),
-        }
+        [
+            (format!("H{}", loc(self.0)), h.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -431,11 +430,11 @@ impl AbstractMeasurement for ElectricField {
         let e = state.sample(self.0).e();
         format!("E{}: {:.2e}", loc(self.0), e)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let e = state.sample(self.0).e();
-        b_tree_map! {
-            format!("E{}", loc(self.0)) => e.to_string(),
-        }
+        [
+            (format!("E{}", loc(self.0)), e.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -478,11 +477,11 @@ impl AbstractMeasurement for Energy {
         let e = self.data(state);
         format!("U({}): {:.2e}", self.name, e)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let e = self.data(state);
-        b_tree_map! {
-            format!("U({})", self.name) => e.to_string(),
-        }
+        [
+            (format!("U({})", self.name), e.to_string()),
+        ].into_iter().collect()
     }
 }
 
@@ -520,10 +519,10 @@ impl AbstractMeasurement for Power {
         let power = self.data(state);
         format!("P({}): {:.2e}", self.name, power)
     }
-    fn key_value(&self, state: &dyn GenericSim) -> BTreeMap<String, String> {
+    fn key_value(&self, state: &dyn GenericSim) -> IndexMap<String, String> {
         let power = self.data(state);
-        b_tree_map! {
-            format!("P({})", self.name) => power.to_string(),
-        }
+        [
+            (format!("P({})", self.name), power.to_string()),
+        ].into_iter().collect()
     }
 }
diff --git a/src/render.rs b/src/render.rs
index 2786d82..19984f8 100644
--- a/src/render.rs
+++ b/src/render.rs
@@ -784,6 +784,7 @@ impl<S: GenericSim> Renderer<S> for CsvRenderer {
             CsvState::Writing(writer) => writer,
         };
         writer.write_record(row.values()).unwrap();
+        writer.flush().unwrap();
         *lock = Some(CsvState::Writing(writer));
     }
 }