NeilFraser · NeilFraser · May 25, 2026
diff --git a/Blockly/framework/List-test.agc b/Blockly/framework/List-test.agc
@@ -0,0 +1,33 @@
+# Unit tests for the List functions.
+
+# TEST: SET
+
+	CA	NUM4		# list[0] -> 4
+	TCR	PUSH
+	CA	NUM0
+	TCR	PUSH
+	TCR	LS-SET
+	CA	NUM2		# list[1] -> 2
+	TCR	PUSH
+	CA	NUM1
+	TCR	PUSH
+	TCR	LS-SET
+
+	CA	NUM4		# Test that list[0] == 4
+	TCR	PUSH
+	CA	LIST
+	TCR	PUSH
+	TCR	TS-EQUAL
+
+	CA	NUM2		# Test that list[1] == 2
+	TCR	PUSH
+	CA	NUM1
+	COM
+	INDEX	A
+	CA	LIST
+	TCR	PUSH
+	TCR	TS-EQUAL
+
+# Blockly will normally define list.
+# But for tests, it otherwise wouldn't be defined.
+LIST	=	3777
diff --git a/Blockly/framework/List.agc b/Blockly/framework/List.agc
@@ -0,0 +1,18 @@
+# List functions.
+
+# Set.
+# Stack arguments:
+#       Value.
+#       Index.
+# Uses L register.
+LS-SET		EXTEND
+		QXCH	QPOP
+		TCR	POP	# Pop the index.
+		COM
+		TS	L
+		TCR	POP	# Pop the value.
+		INDEX	L
+		TS	LIST
+		EXTEND
+		QXCH	QPOP
+		RETURN
diff --git a/Blockly/framework/Main.agc b/Blockly/framework/Main.agc
@@ -98,6 +98,7 @@ END		CA	A
 
 # Code modules.
 $Boolean.agc
+$List.agc
 $Math.agc
 $Print.agc
 $Random.agc

diff --git a/Blockly/framework/Tests.agc b/Blockly/framework/Tests.agc
@@ -2,6 +2,7 @@
 
 # Execute the tests.
 $Boolean-test.agc
+$List-test.agc
 $Math-test.agc
 $Random-test.agc
 $Print-test.agc

diff --git a/Blockly/html/agc/blocks/lists.js b/Blockly/html/agc/blocks/lists.js
@@ -0,0 +1,46 @@
+/**
+ * @fileoverview List blocks for Blockly.
+ */
+'use strict';
+
+Blockly.defineBlocksWithJsonArray([
+  // Block for list item setter.
+  {
+    "type": "list_set",
+    "message0": "set list at %1 to %2",
+    "args0": [
+      {
+        'type': 'input_value',
+        'name': 'INDEX',
+        'check': 'Number',
+      },
+      {
+        'type': 'input_value',
+        'name': 'VALUE',
+        'check': 'Number',
+      },
+    ],
+    "previousStatement": null,
+    "nextStatement": null,
+    "inputsInline": true,
+    "style": "list_blocks",
+    "helpUrl": null,
+    "tooltip": "Set the value in the list at the specified location.",
+  },
+  // Block for list item getter.
+  {
+    "type": "list_get",
+    "message0": "get list at %1",
+    "args0": [
+      {
+        'type': 'input_value',
+        'name': 'INDEX',
+        'check': 'Number',
+      },
+    ],
+    "output": null,
+    "style": "list_blocks",
+    "helpUrl": null,
+    "tooltip": "Get the value in the list at the specified location.",
+  },
+]);
diff --git a/Blockly/html/agc/generator/generator.js b/Blockly/html/agc/generator/generator.js
@@ -72,16 +72,18 @@ AgcGenerator.init = function(workspace) {
   }
 
   // Declare all of the variables.
-  if (defvars.length) {
-    // Octal 4000 is just beyond the end of AGC's erasable memory.
-    // Declare variables starting from the end of memory and working downwards.
-    let memoryAddress = 0o4000;
-    this.definitions_['variables'] = '';
-    for (const varName of defvars) {
-      memoryAddress--;
-      this.definitions_['variables'] += varName + '\t=\t' + memoryAddress.toString(8) + '\n';
-    }
+  // Octal 4000 is just beyond the end of AGC's erasable memory.
+  // Declare variables starting from the end of memory and working downwards.
+  let memoryAddress = 0o4000;
+  this.definitions_['variables'] = '';
+  for (const varName of defvars) {
+    memoryAddress--;
+    this.definitions_['variables'] += varName + '\t=\t' + memoryAddress.toString(8) + '\n';
   }
+  // Final variable is the list.
+  memoryAddress--;
+  this.definitions_['variables'] += 'LIST\t=\t' + memoryAddress.toString(8) + '\n';
+
   this.isInitialized = true;
 };
 

diff --git a/Blockly/html/agc/generator/lists.js b/Blockly/html/agc/generator/lists.js
@@ -0,0 +1,33 @@
+/**
+ * @fileoverview Generating AGC assembly for list blocks.
+ */
+'use strict';
+
+AgcGenerator['list_get'] = function(block) {
+  // List item getter.
+  const argument0 = AgcGenerator.valueToCode(block, 'INDEX') ||
+      AgcGenerator.default0;
+  const code = `
+${argument0}
+\tCOM
+\tINDEX\tA
+\tCA\tLIST
+`;
+  return code;
+};
+
+AgcGenerator['list_set'] = function(block) {
+  // List item setter.
+  const argument0 = AgcGenerator.valueToCode(block, 'INDEX') ||
+      AgcGenerator.default0;
+  const argument1 = AgcGenerator.valueToCode(block, 'VALUE') ||
+      AgcGenerator.default0;
+  const code = `
+${argument1}
+\tTCR\tPUSH
+${argument0}
+\tTCR\tPUSH
+\tTCR\tLS-SET
+`;
+  return code;
+};
diff --git a/Blockly/html/agc/index.html b/Blockly/html/agc/index.html
@@ -14,13 +14,15 @@
   -->
   <script src="storage.js"></script>
   <script src="blocks/agc.js"></script>
+  <script src="blocks/lists.js"></script>
   <script src="blocks/logic.js"></script>
   <script src="blocks/loops.js"></script>
   <script src="blocks/math.js"></script>
   <script src="blocks/procedures.js"></script>
   <script src="blocks/variables.js"></script>
   <script src="generator/generator.js"></script>
   <script src="generator/agc.js"></script>
+  <script src="generator/lists.js"></script>
   <script src="generator/logic.js"></script>
   <script src="generator/loops.js"></script>
   <script src="generator/math.js"></script>
@@ -71,6 +73,33 @@ <h1>Blockly AGC</h1>
   <textarea id="content_xml" class="content" wrap="off"></textarea>
 
   <xml xmlns="https://developers.google.com/blockly/xml" id="toolbox" style="display: none">
+    <category name="AGC" colour="%{BKY_COLOUR_HUE}">
+      <block type="agc_print_digit">
+        <value name="DIGIT">
+          <shadow type="math_number">
+            <field name="NUM">0</field>
+          </shadow>
+        </value>
+        <value name="COL">
+          <shadow type="math_number">
+            <field name="NUM">0</field>
+          </shadow>
+        </value>
+        <value name="ROW">
+          <shadow type="math_number">
+            <field name="NUM">0</field>
+          </shadow>
+        </value>
+      </block>
+      <block type="agc_key_press"></block>
+      <block type="agc_sleep">
+        <value name="TIME">
+          <shadow type="math_number">
+            <field name="NUM">100</field>
+          </shadow>
+        </value>
+      </block>
+    </category>
     <category name="Logic" colour="%{BKY_LOGIC_HUE}">
       <block type="logic_if"></block>
       <block type="logic_ifelse"></block>
@@ -119,34 +148,28 @@ <h1>Blockly AGC</h1>
         </value>
       </block>
     </category>
-    <category name="AGC" colour="%{BKY_COLOUR_HUE}">
-      <block type="agc_print_digit">
-        <value name="DIGIT">
-          <shadow type="math_number">
-            <field name="NUM">0</field>
-          </shadow>
-        </value>
-        <value name="COL">
+    <sep></sep>
+    <category name="List" colour="%{BKY_LISTS_HUE}">
+      <block type="list_set">
+        <value name="INDEX">
           <shadow type="math_number">
             <field name="NUM">0</field>
           </shadow>
         </value>
-        <value name="ROW">
+        <value name="VALUE">
           <shadow type="math_number">
             <field name="NUM">0</field>
           </shadow>
         </value>
       </block>
-      <block type="agc_key_press"></block>
-      <block type="agc_sleep">
-        <value name="TIME">
+      <block type="list_get">
+        <value name="INDEX">
           <shadow type="math_number">
-            <field name="NUM">100</field>
+            <field name="NUM">0</field>
           </shadow>
         </value>
       </block>
     </category>
-    <sep></sep>
     <category name="Variables" colour="%{BKY_VARIABLES_HUE}" custom="VARIABLE"></category>
     <category name="Functions" colour="%{BKY_PROCEDURES_HUE}" custom="PROCEDURE"></category>
   </xml>