diff --git a/Cargo.lock b/Cargo.lock
index e6d43dc..8c381be 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,6 +2,12 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "a1"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8470e27ace1e4691e30b3c05a719397c10e799d3ed1814dad8d6797580d9ddd"
+
 [[package]]
 name = "allocator-api2"
 version = "0.2.18"
@@ -425,6 +431,7 @@ checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 name = "sheetui"
 version = "0.1.0"
 dependencies = [
+ "a1",
  "clap",
  "crossterm",
  "ratatui",
diff --git a/Cargo.toml b/Cargo.toml
index 09699f6..e47228c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,6 +6,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+a1 = "1.0.1"
 clap = { version = "4.5.20", features = ["derive"] }
 crossterm = "0.28.1"
 ratatui = "0.29.0"
diff --git a/src/main.rs b/src/main.rs
index 1536935..ed209ce 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,9 +5,12 @@ use crossterm::event::{self, Event, KeyCode, KeyEventKind};
 use ratatui::{
     self,
     layout::{Constraint, Layout},
-    widgets::{Cell, Row, Table, Tabs},
+    widgets::{Table, Tabs},
     Frame,
 };
+use sheet::{Address, Computable, Tbl};
+
+mod sheet;
 
 #[derive(Parser, Debug)]
 #[command(version, about, long_about = None)]
@@ -27,20 +30,17 @@ fn run(terminal: &mut ratatui::DefaultTerminal) -> std::io::Result<()> {
     }
 }
 
-fn generate_default_rows<'a>(row_count: usize, col_count: usize) -> Vec<Row<'a>> {
-    (0..row_count)
-        .map(|ri| {
-            (0..col_count)
-                .map(|ci| Cell::new(format!(" {}:{} ", ri, ci)))
-                .collect::<Row>()
-                .height(2)
-        })
-        .collect::<Vec<Row>>()
+fn generate_default_table<'a>() -> Table<'a> {
+    let mut tbl = Tbl::new();
+    tbl.update_entry(Address::new(5, 5), Computable::Text("loc: 5, 5".to_owned()));
+    tbl.update_entry(Address::new(10, 10), Computable::Number(10.10));
+    tbl.update_entry(Address::new(0, 0), Computable::Formula("".to_owned()));
+    tbl.into()
 }
 
 fn draw(frame: &mut Frame) {
     use Constraint::{Min, Percentage};
-    let table = Table::default().rows(generate_default_rows(10, 10));
+    let table = generate_default_table();
     let tabs = Tabs::new(vec!["sheet1"]).select(0);
     let rects = Layout::vertical([Min(1), Percentage(90)]).split(frame.area());
 
@@ -49,8 +49,8 @@ fn draw(frame: &mut Frame) {
 }
 
 fn main() -> std::io::Result<()> {
-    let args = Args::parse();
-    
+    let _ = Args::parse();
+
     let mut terminal = ratatui::init();
     terminal.clear()?;
     let app_result = run(&mut terminal);
diff --git a/src/sheet/mod.rs b/src/sheet/mod.rs
new file mode 100644
index 0000000..749cdb3
--- /dev/null
+++ b/src/sheet/mod.rs
@@ -0,0 +1,94 @@
+//! DataModel for a SpreadSheet
+//!
+//! # Overview
+//!
+//! Sheets can contain a [Tbl]. Tbl's contain a collection of [Address] to [Computable]
+//! associations. From this we can compute the dimensions of a Tbl as well as render
+//! them into a [Table] Widget.
+
+use ratatui::widgets::{Cell, Row, Table};
+
+use std::collections::BTreeMap;
+
+/// The Address in a [Tbl].
+#[derive(Default, Debug, PartialEq, PartialOrd, Ord, Eq)]
+pub struct Address {
+    row: usize,
+    col: usize,
+}
+
+impl Address {
+    pub fn new(row: usize, col: usize) -> Self {
+        Self { row, col }
+    }
+}
+
+/// The computable value located at an [Address].
+#[derive(Debug)]
+pub enum Computable {
+    Text(String),
+    Number(f64),
+    Formula(String),
+}
+
+impl Default for Computable {
+    fn default() -> Self {
+        Self::Text("".to_owned())
+    }
+}
+
+/// A single table of addressable computable values.
+#[derive(Default, Debug)]
+pub struct Tbl {
+    addresses: BTreeMap<Address, Computable>,
+}
+
+impl Tbl {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn dimensions(&self) -> (usize, usize) {
+        let (mut row, mut col) = (0, 0);
+        for (addr, _) in &self.addresses {
+            row = std::cmp::max(row, addr.row);
+            col = std::cmp::max(col, addr.col);
+        }
+        (row, col)
+    }
+
+    pub fn get_computable(&self, row: usize, col: usize) -> Option<&Computable> {
+        self.addresses.get(&Address::new(row, col))
+    }
+
+    pub fn update_entry(&mut self, address: Address, computable: Computable) {
+        // TODO(zaphar): At some point we'll need to store the graph of computation
+        // dependencies
+        self.addresses.insert(address, computable);
+    }
+}
+
+impl<'t> From<Tbl> for Table<'t> {
+    fn from(value: Tbl) -> Self {
+        let (row, col) = value.dimensions();
+        let rows = (0..=row)
+            .map(|ri| {
+                (0..=col)
+                    .map(|ci| {
+                        match value.get_computable(ri, ci) {
+                            // TODO(zaphar): Style information
+                            Some(Computable::Text(s)) => Cell::new(format!(" {}", s)),
+                            Some(Computable::Number(f)) => Cell::new(format!(" {}", f)),
+                            Some(Computable::Formula(_expr)) => Cell::new(format!(" .formula. ")),
+                            None => Cell::new(format!(" {}:{} ", ri, ci)),
+                        }
+                    })
+                    .collect::<Row>()
+            })
+            .collect::<Vec<Row>>();
+        Table::default().rows(rows)
+    }
+}
+
+#[cfg(test)]
+mod tests;
diff --git a/src/sheet/tests.rs b/src/sheet/tests.rs
new file mode 100644
index 0000000..90be3c4
--- /dev/null
+++ b/src/sheet/tests.rs
@@ -0,0 +1,12 @@
+use super::*;
+
+#[test]
+fn test_dimensions_calculation() {
+    let mut tbl = Tbl::new();
+    tbl.update_entry(Address::new(0, 0), Computable::Text(String::new()));
+    assert_eq!((0, 0), tbl.dimensions());
+    tbl.update_entry(Address::new(0, 10), Computable::Text(String::new()));
+    assert_eq!((0, 10), tbl.dimensions());
+    tbl.update_entry(Address::new(20, 5), Computable::Text(String::new()));
+    assert_eq!((20, 10), tbl.dimensions());
+}