diff --git a/font_maker/font_maker.js b/font_maker/font_maker.js
new file mode 100644
index 0000000..0a933c6
--- /dev/null
+++ b/font_maker/font_maker.js
@@ -0,0 +1,194 @@
+const canvas = document.querySelector("#canvas");
+const selectedDiv = document.querySelector("#selected");
+const charlistTable = document.querySelector("#charlist");
+const exportButton = document.querySelector("#export");
+const exportAreaCode = document.querySelector("#export-area");
+
+const [width, height] = [400, 400];
+
+canvas.width = width;
+canvas.height = height;
+
+canvas.style.width = width + "px";
+canvas.style.height = height + "px";
+
+const g = canvas.getContext("2d");
+g.imageSmoothingEnabled = false;
+
+const state = new Array(64).fill(false);
+
+function render() {
+    g.fillStyle = "black";
+    g.fillRect(0, 0, width, height);
+    g.fillStyle = "white";
+    for (let y = 0; y < 8; ++y) {
+        for (let x = 0; x < 8; ++x) {
+            if (state[y * 8 + x]) {
+                g.fillRect(
+                    x * (width / 8),
+                    y * (height / 8),
+                    width / 8,
+                    height / 8,
+                );
+            }
+        }
+    }
+    renderGrid();
+}
+
+function renderGrid() {
+    g.strokeStyle = "gray";
+    g.lineWidth = 1;
+    g.beginPath();
+    for (let y = 0; y < 8; ++y) {
+        for (let x = 0; x < 8; ++x) {
+            g.moveTo(x * (width / 8), 0);
+            g.lineTo(x * (width / 8), height);
+            g.moveTo(0, y * (height / 8));
+            g.lineTo(width, y * (height / 8));
+        }
+    }
+    g.moveTo(width - 1, 0);
+    g.lineTo(width - 1, height);
+    g.moveTo(0, height - 1);
+    g.lineTo(width, height - 1);
+    g.stroke();
+}
+
+const specialChars = Object.fromEntries(
+    Object.entries({
+        "\0": "0",
+        "\n": "n",
+        "\r": "r",
+        "\t": "t",
+    }).map(([ch, r]) => [ch.charCodeAt(0), "\\" + r]),
+);
+
+const chars = new Array(127).fill(0).map((_, i) => ({
+    i,
+    ch: specialChars[i] ?? (i > 31 ? String.fromCharCode(i) : ""),
+    hex: new Array(8).fill(0),
+}));
+
+let selected = { i: 0, ch: "\0", hex: new Array(8).fill(0) };
+
+function stateToHex(state) {
+    let hex = new Array(8).fill(0);
+    for (let y = 0; y < 8; ++y) {
+        let byte = 0;
+        for (let x = 0; x < 8; ++x) {
+            if (state[y * 8 + x]) {
+                byte |= 1 << 7 - x;
+            }
+        }
+        hex[y] = byte;
+    }
+    return hex;
+}
+
+function stateFromHex(state, hex) {
+    for (let y = 0; y < 8; ++y) {
+        for (let x = 0; x < 8; ++x) {
+            state[y * 8 + x] = (hex[y] >> 7 - x & 1) != 0;
+        }
+    }
+}
+
+function html(strings, ...values) {
+    return strings[0] +
+        strings.slice(1).map((v, i) => values[i].toString() + v).join("");
+}
+
+function renderSelectedChar() {
+    const { i, ch, hex } = selected;
+    selectedDiv.innerHTML = html`
+        <span><code>${i}</code></span>
+        <span><code>${ch}</code></span>
+        <span><code>0x${hex.map((v) => v.toString(16).padStart(2, "0")).join(
+            "",
+        )}</code></span>
+        <span><input type="text" id="overwrite"></span>
+        <span><button id="selected-save">Save</button></span>
+    `;
+
+    document.querySelector("#selected-save")
+        .onclick = () => {
+            const overwrite = document.querySelector("#overwrite").value;
+            if (overwrite) {
+                const hex = new Array(8).fill(0);
+                for (let i = 0; i < 8; ++i) {
+                    hex[i] = parseInt(
+                        overwrite.slice(i * 2 + 2, i * 2 + 4),
+                        16,
+                    );
+                }
+                chars[selected.i].hex = hex;
+                selected.hex = hex.map((v) => v);
+                stateFromHex(state, hex);
+                renderCharlist();
+                renderSelectedChar();
+                render();
+            } else {
+                chars[selected.i].hex = selected.hex.map((v) => v);
+                renderCharlist();
+            }
+        };
+}
+
+function renderCharlist() {
+    charlistTable.innerHTML = html`
+        <tr>
+            <td>int</td>
+            <td>char</td>
+            <td>hex</td>
+            <td>action</td>
+        </tr>
+    ` + chars
+        .map(({ i, ch, hex }) =>
+            html`
+                <tr>
+                    <td><code>${i}</code></td>
+                    <td><code>${ch}</code></td>
+                    <td><code>0x${hex.map((v) =>
+                        v.toString(16).padStart(2, "0")
+                    ).join("")}</code></td>
+                    <td><button id="char-select-${i}">Select</button></td>
+                </tr>
+            `
+        ).join("");
+
+    for (const char of chars) {
+        const { i, ch, hex } = char;
+        document.querySelector(`#char-select-${i}`)
+            .onclick = () => {
+                selected = { i, ch, hex: hex.map((v) => v) };
+                renderSelectedChar();
+                stateFromHex(state, selected.hex);
+                render();
+            };
+    }
+}
+
+canvas.onclick = (ev) => {
+    const [x, y] = [ev.offsetX / width * 8, ev.offsetY / height * 8].map(
+        Math.floor,
+    );
+    state[y * 8 + x] = !state[y * 8 + x];
+    render();
+    selected.hex = stateToHex(state);
+    renderSelectedChar();
+};
+
+renderSelectedChar();
+render();
+renderCharlist();
+
+exportButton.onclick = () => {
+    exportAreaCode.innerText = chars.map(({ i, ch, hex }) =>
+        `
+        case ${ch != "" ? `'${ch}'` : i}: return 0x${
+            hex.map((v) => v.toString(16).padStart(2, "0")).join("")
+        };
+    `.trim()
+    ).join("\n");
+};
diff --git a/font_maker/index.html b/font_maker/index.html
new file mode 100644
index 0000000..9f7814f
--- /dev/null
+++ b/font_maker/index.html
@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Document</title>
+    <script src="./font_maker.js" type="module" defer></script>
+
+    <style>
+        :root {
+            color-scheme: light dark;
+        }
+        * {
+            box-sizing: border-box;
+        }
+        table {
+            border-collapse: collapse;
+        }
+        td {
+            border-top: 1px solid gray;
+            min-width: 70px;
+            text-align: center;
+            padding: 4px;
+        }
+        #selected {
+            display: flex;
+            flex-direction: row;
+            border-top: 1px solid gray;
+            padding: 10px;
+        }
+        #selected > * {
+            min-width: 70px;
+            text-align: center;
+        }
+        code {
+            font-size: 18px;
+            background-color: #444;
+            padding: 2px;
+            padding-left: 4px;
+            padding-right: 4px;
+            border-radius: 2px;
+        }
+    </style>
+</head>
+<body>
+    <canvas id="canvas"></canvas>
+    <div id="selected"></div>
+    <table id="charlist"></table>
+    <button id="export">Export</button>
+    <pre><code id="export-area"></code></pre>
+</body>
+</html>
diff --git a/src/io_device.cpp b/src/io_device.cpp
index 37bf01d..fa149ea 100644
--- a/src/io_device.cpp
+++ b/src/io_device.cpp
@@ -20,6 +20,21 @@ constexpr uint64_t char_data(uint8_t ch)
     switch (ch) {
             // clang-format off
         case ' ': return 0x0000000000000000;
+        case '!': return 0x0018181818001818;
+        case '"': return 0x0066660000000000;
+        case '#': return 0x00247e24247e2400;
+        case '$': return 0x00187e6218467e18;
+        case '%': return 0x0022562c18346a44;
+        case '&': return 0x00784c38724a4638;
+        case '\'': return 0x0018180000000000;
+        case '(': return 0x000c18303030180c;
+        case ')': return 0x0030180c0c0c1830;
+        case '*': return 0x0000241818240000;
+        case '+': return 0x000018187e7e1818;
+        case ',': return 0x0000000000181830;
+        case '-': return 0x000000007e7e0000;
+        case '.': return 0x0000000000181800;
+        case '/': return 0x0002060c18306040;
 
         case '0': return 0x003C666E7666663C;
         case '1': return 0x001838181818183C;
@@ -32,6 +47,14 @@ constexpr uint64_t char_data(uint8_t ch)
         case '8': return 0x003C66663C66663C;
         case '9': return 0x003C66663E06663C;
 
+        case ':': return 0x0018180000181800;
+        case ';': return 0x0000181800181830;
+        case '<': return 0x00060c1830180c06;
+        case '=': return 0x00007e7e007e7e00;
+        case '>': return 0x006030180c183060;
+        case '?': return 0x003e660c18001818;
+        case '@': return 0x003c664a564e603c;
+
         case 'A': return 0x00187E66667E6666;
         case 'B': return 0x00787E667C667E7C;
         case 'C': return 0x003C7E6060607E3C;
@@ -59,7 +82,42 @@ constexpr uint64_t char_data(uint8_t ch)
         case 'Y': return 0x0066663C18181818;
         case 'Z': return 0x007E7E0C18307E7E;
 
-        case ':': return 0x0018180000181800;
+        case '[': return 0x003c30303030303c;
+        case '\\': return 0x00406030180c0602;
+        case ']': return 0x003c0c0c0c0c0c3c;
+        case '^': return 0x0010386c44000000;
+        case '_': return 0x00000000000000ff;
+        case '`': return 0x0030181800000000;
+        case 'a': return 0x0000003c023e423e;
+        case 'b': return 0x004040407c42427c;
+        case 'c': return 0x000000003c40403c;
+        case 'd': return 0x00020202023e423e;
+        case 'e': return 0x0000003c427c403c;
+        case 'f': return 0x00000c103c101010;
+        case 'g': return 0x003e645840784438;
+        case 'h': return 0x0020202038242424;
+        case 'i': return 0x0000181800181818;
+        case 'j': return 0x000606000606361c;
+        case 'k': return 0x0020202c3830382c;
+        case 'l': return 0x003010101010100c;
+        case 'm': return 0x000000203e2a2a2a;
+        case 'n': return 0x0000000038242424;
+        case 'o': return 0x0000000018242418;
+        case 'p': return 0x0000001c223c2020;
+        case 'q': return 0x00000018241c0404;
+        case 'r': return 0x0000002038242020;
+        case 's': return 0x0000003840380438;
+        case 't': return 0x0000103c1010100c;
+        case 'u': return 0x000000002424241e;
+        case 'v': return 0x0000002424243c18;
+        case 'w': return 0x0000000063222a3e;
+        case 'x': return 0x000000663c183c66;
+        case 'y': return 0x00000024241c0438;
+        case 'z': return 0x0000003e060c183e;
+        case '{': return 0x000c18183018180c;
+        case '|': return 0x1818181818181818;
+        case '}': return 0x003018180c181830;
+        case '~': return 0x0000307a5e0c0000;
 
         default:  return 0x55AA55AA55AA55AA;
             // clang-format on