diff --git a/ecsroot/vcs/kernel.ecs b/ecsroot/vcs/kernel.ecs
deleted file mode 100644
index 67674fd6..00000000
--- a/ecsroot/vcs/kernel.ecs
+++ /dev/null
@@ -1,279 +0,0 @@
-
-component Kernel
-    lines: 0..255
-    bgcolor: 0..255
-end
-
-component Bitmap
-    bitmapdata: array of 0..255
-end
-
-component HasBitmap
-    bitmap: [Bitmap]
-end
-
-component Colormap
-    colormapdata: array of 0..255
-end
-
-component HasColormap
-    colormap: [Colormap]
-end
-
-component Sprite
-    height: 0..255
-    plyrindex: 0..1
-end
-
-component Player end
-
-component PlayerFlags
-    plyrflags: 0..63
-end
-
-component HasXpos
-    xpos: 0..255
-end
-
-component HasYpos
-    ypos: 0..255
-end
-
-component HasXYVel
-    xyvel: 0..255
-end
-
-system FrameLoop
-    on start do once [Kernel] emit (preframe, kernel, postframe)
----
-{{@NextFrame}}:
-    FRAME_START
-    {{!preframe}}
-    KERNEL_START
-    {{!kernel}}
-    KERNEL_END
-    {{!postframe}}
-    FRAME_END
-    lsr SWCHB	    ; test Game Reset switch
-    bcs {{@NoStart}}
-    jmp Start
-{{@NoStart}}:
-    jmp {{@NextFrame}}
----
-end
-
-system SimpleKernel
-    locals 12
-    on preframe do each [Sprite,HasBitmap,HasColormap,HasYpos]
----
-    lda #192 ; TODO: numlines
-    sec
-    sbc {{<ypos}}
-    sta {{$11}}
-
-    ldy {{<bitmap}}         ; deref
-    lda {{<Bitmap.bitmapdata}},y
-    sec
-    sbc {{$11}}
-    sta {{$0}},x
-    lda {{>Bitmap.bitmapdata}},y
-    sbc #0
-    sta {{$2}},x
-
-    ldy {{<colormap}}
-    lda {{<Colormap.colormapdata}},y
-    sec
-    sbc {{$11}}
-    sta {{$4}},x
-    lda {{>Colormap.colormapdata}},y
-    sbc #0
-    sta {{$6}},x
-
-    lda {{<height}}
-    sta {{$8}},x
-    lda {{<ypos}}
-    sta {{$10}},x
----
-    on preframe do once [Sprite,HasBitmap,HasColormap,HasYpos]
----
-; L0 L1 H0 H1 -> L0 H0 L1 H1
-    lda {{$1}}
-    ldy {{$2}}
-    sty {{$1}}
-    sta {{$2}}
-    lda {{$5}}
-    ldy {{$6}}
-    sty {{$5}}
-    sta {{$6}}
----
-    on kernel do once [Kernel]
----
-    lda {{<bgcolor}}
-    sta COLUBK
-    ldy {{<lines}}
-@LVScan:
-    lda {{$8}} ; height
-    dcp {{$10}} ; ypos
-    bcs @DoDraw1
-    lda #0
-    .byte $2C
-@DoDraw1:
-    lda ({{$0}}),y
-    sta WSYNC
-    sta GRP0
-    lda ({{$4}}),y
-    sta COLUP0
-
-    lda {{$9}} ; height
-    dcp {{$11}} ; ypos
-    bcs @DoDraw2
-    lda #0
-    .byte $2C
-@DoDraw2:
-    lda ({{$2}}),y
-    sta GRP1
-    lda ({{$6}}),y
-    sta COLUP1
-
-    dey		; decrement
-    bne @LVScan	; repeat until 192 lines
----
-end
-
-system SetXPos
-    on preframe do each [Sprite,HasXpos] emit (SetHorizPos)
----
-    lda {{<xpos}}
-    ldy {{<plyrindex}}
-    sta HMCLR
-    jsr {{^SetHorizPos}}
----
-end
-
-system SetHorizPos
-    on SetHorizPos do once [HasXpos]
----
-; SetHorizPos routine
-; A = X coordinate
-; Y = player number (0 or 1)
-SetHorizPos:
-	sta WSYNC	; start a new line
-	sec		    ; set carry flag
-    nop
-@DivideLoop:
-	sbc #15		; subtract 15
-	bcs @DivideLoop	; branch until negative
-	eor #7		; calculate fine offset
-	asl
-	asl
-	asl
-	asl
-	sta RESP0,y	; fix coarse position
-	sta HMP0,y	; set fine offset
-    sta WSYNC
-    sta HMOVE
-	rts		; return to caller
----
-end
-
-system JoyRead
-    locals 1
-    on postframe do once [Player]
----
-    lda SWCHA
-    sta {{$0}}
----
-    on postframe do each [Player] emit (joyup, joydown, joyleft, joyright, joybutton)
----
-    asl {{$0}}
-    bcs {{@SkipMoveRight}}
-    {{!joyright}}
-{{@SkipMoveRight}}:
-    asl {{$0}}
-    bcs {{@SkipMoveLeft}}
-    {{!joyleft}}
-{{@SkipMoveLeft}}:
-    asl {{$0}}
-    bcs {{@SkipMoveDown}}
-    {{!joydown}}
-{{@SkipMoveDown}}:
-    asl {{$0}}
-    bcs {{@SkipMoveUp}}
-    {{!joyup}}
-{{@SkipMoveUp}}:
----
-end
-
-system MoveJoyX
-    on joyleft do source [HasXpos]
----
-    lda {{<xpos}}
-    sec
-    sbc #1
-    bcc {{@nomove}}
-    sta {{<xpos}}
-{{@nomove}}:
----
-    on joyright do source [HasXpos]
----
-    lda {{<xpos}}
-    clc
-    adc #1
-    cmp #150
-    bcs {{@nomove}}
-    sta {{<xpos}}
-{{@nomove}}:
----
-end
-
-system MoveJoyY
-    on joyup do source [HasYpos]
----
-    lda {{<ypos}}
-    sec
-    sbc #1
-    bcc {{@nomove}}
-    sta {{<ypos}}
-{{@nomove}}:
----
-    on joydown do source [HasYpos]
----
-    lda {{<ypos}}
-    clc
-    adc #1
-    cmp #150
-    bcs {{@nomove}}
-    sta {{<ypos}}
-{{@nomove}}:
----
-end
-
-scope Main
-    entity Kernel [Kernel]
-        const lines = 192
-        const bgcolor = 0xa2
-    end
-    entity Bitmap1 [Bitmap]
-        const bitmapdata = [1, 1, 3, 7, 15, 31, 63, 127]
-    end
-    entity Bitmap2 [Bitmap]
-        const bitmapdata = [$18,$3e,$ff,$ff,$ff,$ff,$3e,$18]
-    end
-    entity Colormap1 [Colormap]
-        const colormapdata = [6, 3, 6, 9, 12, 14, 31, 63]
-    end
-    entity Player0 [Sprite,HasBitmap,HasColormap,HasXpos,HasYpos,Player]
-        const plyrindex = 0
-        init height = 8
-        init xpos = 50
-        init ypos = 50
-    end
-    entity Player1 [Sprite,HasBitmap,HasColormap,HasXpos,HasYpos,Player]
-        const plyrindex = 1
-        init height = 8
-        init xpos = 100
-        init ypos = 60
-        init bitmap = #Bitmap2
-    end
-end
-
diff --git a/index.html b/index.html
index 6a95a8c0..ac0b20ae 100644
--- a/index.html
+++ b/index.html
@@ -540,6 +540,7 @@ if (window.location.host.endsWith('8bitworkshop.com')) {
 <script src="src/codemirror/basic.js"></script>
 <script src="src/codemirror/wiz.js"></script>
 <script src="src/codemirror/vasm.js"></script>
+<script src="src/codemirror/ecs.js"></script>
 <link rel="stylesheet" href="css/codemirror.css">
 <script src="codemirror/addon/edit/matchbrackets.js"></script>
 <script src="codemirror/addon/search/search.js"></script>
diff --git a/src/codemirror/ecs.js b/src/codemirror/ecs.js
new file mode 100644
index 00000000..eb149db1
--- /dev/null
+++ b/src/codemirror/ecs.js
@@ -0,0 +1,103 @@
+// CodeMirror, copyright (c) by Marijn Haverbeke and others
+// Distributed under an MIT license: http://codemirror.net/LICENSE
+
+(function (mod) {
+  if (typeof exports == "object" && typeof module == "object") // CommonJS
+    mod(require("../../lib/codemirror"));
+  else if (typeof define == "function" && define.amd) // AMD
+    define(["../../lib/codemirror"], mod);
+  else // Plain browser env
+    mod(CodeMirror);
+})(function (CodeMirror) {
+  "use strict";
+
+  // 6502 DASM syntax
+
+  CodeMirror.defineMode('ecs', function (_config, parserConfig) {
+    var keywords1, keywords2;
+
+    var directives_list = [
+      'component', 'system', 'entity', 'scope', 'end',
+      'const', 'init', 'locals',
+      'on', 'do', 'emit',
+      'once', 'foreach', 'source',
+    ];
+    var keywords_list = [
+      'processor',
+      'byte', 'word', 'long',
+      'include', 'seg', 'dc', 'ds', 'dv', 'hex', 'err', 'org', 'rorg', 'echo', 'rend',
+      'align', 'subroutine', 'equ', 'eqm', 'set', 'mac', 'endm', 'mexit', 'ifconst',
+      'ifnconst', 'if', 'else', 'endif', 'eif', 'repeat', 'repend'
+    ];
+
+    var directives = new Map();
+    directives_list.forEach(function (s) { directives.set(s, 'def'); });
+    keywords_list.forEach(function (s) { directives.set(s, 'keyword'); });
+
+    var opcodes = /^[a-z][a-z][a-z]\b/i;
+    var numbers = /^(0x[\da-f]+|[\da-f]+h|[0-7]+o|[01]+b|\d+d?)\b/i;
+    var tags = /^\{\{.*\}\}/;
+    var mlcomment = /^---.+?---\b/i;
+
+    return {
+      startState: function () {
+        return {
+          context: 0
+        };
+      },
+      token: function (stream, state) {
+        if (stream.eatSpace())
+          return null;
+
+        if (stream.match(tags)) {
+          return 'meta';
+        }
+
+        var w;
+        if (stream.eatWhile(/\w/)) {
+          w = stream.current();
+          var cur = w.toLowerCase();
+          var style = directives.get(cur);
+          if (style)
+            return style;
+
+          if (opcodes.test(w)) {
+            return 'keyword';
+          } else if (numbers.test(w)) {
+            return 'number';
+          } else if (w == 'comment') {
+            stream.match(mlcomment);
+            return 'comment';
+          }
+        } else if (stream.eat(';')) {
+          stream.skipToEnd();
+          return 'comment';
+        } else if (stream.eat('"')) {
+          while (w = stream.next()) {
+            if (w == '"')
+              break;
+
+            if (w == '\\')
+              stream.next();
+          }
+          return 'string';
+        } else if (stream.eat('\'')) {
+          if (stream.match(/\\?.'/))
+            return 'number';
+        } else if (stream.eat('$') || stream.eat('#')) {
+          if (stream.eatWhile(/[^;]/i))
+            return 'number';
+        } else if (stream.eat('%')) {
+          if (stream.eatWhile(/[01]/))
+            return 'number';
+        } else {
+          stream.next();
+        }
+        return null;
+      }
+    };
+  });
+
+  CodeMirror.defineMIME("text/x-ecs", "ecs");
+
+});
diff --git a/src/common/ecs/compiler.ts b/src/common/ecs/compiler.ts
index 49761fc9..ba3677c7 100644
--- a/src/common/ecs/compiler.ts
+++ b/src/common/ecs/compiler.ts
@@ -152,7 +152,7 @@ export class ECSCompiler extends Tokenizer {
     parseAction(): Action {
         let event = this.expectIdent().str;
         this.expectToken('do');
-        let select = this.expectTokens(['once', 'each', 'source']).str as SelectType; // TODO: type check?
+        let select = this.expectTokens(['once', 'foreach', 'source']).str as SelectType; // TODO: type check?
         let query = this.parseQuery();
         let emits;
         if (this.peekToken().str == 'emit') {
@@ -183,6 +183,7 @@ export class ECSCompiler extends Tokenizer {
     }
 
     parseCode(): string {
+        // TODO: add $loc
         let tok = this.expectTokenTypes([TokenType.CodeFragment]);
         let code = tok.str;
         let lines = code.split('\n');
diff --git a/src/common/ecs/ecs.ts b/src/common/ecs/ecs.ts
index 5bfb3fd3..019452c2 100644
--- a/src/common/ecs/ecs.ts
+++ b/src/common/ecs/ecs.ts
@@ -97,7 +97,7 @@ export interface Action {
     emits?: string[];
 }
 
-export type SelectType = 'once' | 'each' | 'source';
+export type SelectType = 'once' | 'foreach' | 'source';
 
 export type DataValue = number | boolean | Uint8Array | Uint16Array;
 
@@ -154,11 +154,11 @@ interface ComponentFieldPair {
 export class Dialect_CA65 {
     readonly ASM_ITERATE_EACH = `
     ldx #0
-{{@__each}}:
+@__each:
     {{code}}
     inx
     cpx #{{ecount}}
-    bne {{@__each}}
+    bne @__each
 `;
     readonly INIT_FROM_ARRAY = `
     ldy #{{nbytes}}
@@ -254,13 +254,15 @@ class Segment {
         this.codefrags.push(code);
     }
     allocateBytes(name: string, bytes: number) {
-        if (this.symbols[name]) return this.symbols[name]; // TODO: check size
-        let ofs = this.size;
-        this.symbols[name] = ofs;
-        if (!this.ofs2sym.has(ofs))
-            this.ofs2sym.set(ofs, []);
-        this.ofs2sym.get(ofs)?.push(name);
-        this.size += bytes;
+        let ofs = this.symbols[name];
+        if (ofs == null) {
+            ofs = this.size;
+            this.symbols[name] = ofs;
+            if (!this.ofs2sym.has(ofs))
+                this.ofs2sym.set(ofs, []);
+            this.ofs2sym.get(ofs)?.push(name);
+            this.size += bytes;
+        }
         return ofs;
     }
     // TODO: optimize shared data
@@ -388,7 +390,7 @@ export class EntityScope {
             // variable size? make it a pointer
             if (bits == 0) bits = 16; // TODO?
             let rangelen = (f.ehi - f.elo + 1);
-            let bytesperelem = Math.ceil(bits / 8) * rangelen;
+            let bytesperelem = Math.ceil(bits / 8);
             // TODO: packing bits
             // TODO: split arrays
             f.access = [];
@@ -419,7 +421,7 @@ export class EntityScope {
                     let hiofs = segment.allocateBytes(ptrhisym, entcount);
                     segment.initdata[loofs + e.id - fieldrange.elo] = { symbol: datasym, bitofs: 0 };
                     segment.initdata[hiofs + e.id - fieldrange.elo] = { symbol: datasym, bitofs: 8 };
-                // TODO: } else if (v instanceof Uint16Array) {
+                    // TODO: } else if (v instanceof Uint16Array) {
                 } else if (typeof v === 'number') {
                     // more than 1 entity, add an array
                     // TODO: what if > 8 bits?
@@ -428,6 +430,7 @@ export class EntityScope {
                         let datasym = this.dialect.fieldsymbol(c, f, 0);
                         let base = segment.allocateBytes(datasym, entcount);
                         segment.initdata[base + e.id - fieldrange.elo] = v;
+                        //console.error(cfname, datasym, base, e.id, fieldrange.elo, entcount, v);
                     }
                 } else {
                     throw new ECSError(`unhandled constant ${e.id}:${cfname}`);
@@ -524,17 +527,20 @@ export class EntityScope {
     }
     replaceCode(code: string, sys: System, action: Action): string {
         const re = /\{\{(.+?)\}\}/g;
-        let label = sys.name + '_' + action.event;
+        let label = `${sys.name}__${action.event}`;
         let atypes = this.em.archetypesMatching(action.query);
         let entities = this.entitiesMatching(atypes);
         // TODO: detect cycles
         // TODO: "source"?
         // TODO: what if only 1 item?
-        if (action.select == 'each') {
+        if (action.select == 'foreach') {
             code = this.wrapCodeInLoop(code, sys, action, entities);
             //console.log(sys.name, action.event, ents);
             //frag = this.iterateCode(frag);
         }
+        // replace @labels
+        code = code.replace(/@(\w+)\b/g, (s: string, a: string) => `${label}__${a}`);
+        // replace {{...}} tags
         return code.replace(re, (entire, group: string) => {
             let cmd = group.charAt(0);
             let rest = group.substring(1);
diff --git a/src/ide/ui.ts b/src/ide/ui.ts
index 2c958ba3..c64edde0 100644
--- a/src/ide/ui.ts
+++ b/src/ide/ui.ts
@@ -114,7 +114,8 @@ const TOOL_TO_SOURCE_STYLE = {
   'silice': 'verilog',
   'wiz': 'text/x-wiz',
   'vasmarm': 'vasm',
-  'armips': 'vasm'
+  'armips': 'vasm',
+  'ecs': 'ecs',
 }
 
 const TOOL_TO_HELPURL = {
diff --git a/src/ide/views/editors.ts b/src/ide/views/editors.ts
index d5a81d28..d594ac10 100644
--- a/src/ide/views/editors.ts
+++ b/src/ide/views/editors.ts
@@ -36,6 +36,7 @@ const MODEDEFS = {
   markdown: { lineWrap: true },
   fastbasic: { noGutters: true },
   basic: { noLineNumbers: true, noGutters: true }, // TODO: not used?
+  ecs: { theme: 'mbo', isAsm: false },
 }
 
 export var textMapFunctions = {
diff --git a/src/test/testecs.ts b/src/test/testecs.ts
index 492a76a3..3c3b4438 100644
--- a/src/test/testecs.ts
+++ b/src/test/testecs.ts
@@ -3,7 +3,7 @@ import { ECSCompiler } from "../common/ecs/compiler";
 import { Dialect_CA65, EntityManager, SourceFileExport } from "../common/ecs/ecs";
 
 const TEMPLATE1 = `
-{{@NextFrame}}:
+@NextFrame:
     FRAME_START
     {{!preframe}}
     KERNEL_START
@@ -15,74 +15,12 @@ const TEMPLATE1 = `
     bcs @NoStart
     jmp Start
 @NoStart:
-    jmp {{@NextFrame}}
+    jmp @NextFrame
 `;
 
-// TODO: two sticks?
-const TEMPLATE2_a = `
-    lda SWCHA
-    sta {{$0}}
-`
-
-const TEMPLATE2_b = `
-    asl {{$0}}
-    bcs {{@SkipMoveRight}}
-    {{!joyright}}
-{{@SkipMoveRight}}:
-    asl {{$0}}
-    bcs {{@SkipMoveLeft}}
-    {{!joyleft}}
-{{@SkipMoveLeft}}:
-    asl {{$0}}
-    bcs {{@SkipMoveDown}}
-    {{!joydown}}
-{{@SkipMoveDown}}:
-    asl {{$0}}
-    bcs {{@SkipMoveUp}}
-    {{!joyup}}
-{{@SkipMoveUp}}:
-`;
-
-const TEMPLATE3_L = `
-    lda {{<xpos}}
-    sec
-    sbc #1
-    bcc {{@nomove}}
-    sta {{<xpos}}
-{{@nomove}}:
-`;
-
-const TEMPLATE3_R = `
-    lda {{<xpos}}
-    clc
-    adc #1
-    cmp #150
-    bcs {{@nomove}}
-    sta {{<xpos}}
-{{@nomove}}:
-`;
-
-const TEMPLATE3_U = `
-    lda {{<ypos}}
-    sec
-    sbc #1
-    bcc {{@nomove}}
-    sta {{<ypos}}
-{{@nomove}}:
-`;
-
-const TEMPLATE3_D = `
-    lda {{<ypos}}
-    clc
-    adc #1
-    cmp #150
-    bcs {{@nomove}}
-    sta {{<ypos}}
-{{@nomove}}:
-`;
 
 const TEMPLATE4_S1 = `
-.macro {{@KernelSetup}} ent,ofs
+.macro @KernelSetup ent,ofs
     lda #192 ; TODO: numlines
     sec
     sbc ypos_ypos_b0+ent
@@ -113,8 +51,8 @@ const TEMPLATE4_S1 = `
 .endmacro
 `
 const TEMPLATE4_S2 = `
-    {{@KernelSetup}} 0,0
-    {{@KernelSetup}} 1,6
+    @KernelSetup 0,0
+    @KernelSetup 1,6
 `
 
 // https://atariage.com/forums/topic/75982-skipdraw-and-graphics/?tab=comments#comment-928232
@@ -261,12 +199,6 @@ function testECS() {
             { name: 'ypos', dtype: 'int', lo: 0, hi: 255 }
         ]
     })
-    let c_xyvel = em.defineComponent({
-        name: 'xyvel', fields: [
-            { name: 'xvel', dtype: 'int', lo: -8, hi: 7 },
-            { name: 'yvel', dtype: 'int', lo: -8, hi: 7 }
-        ]
-    })
 
     // init -> [start] -> frameloop
     // frameloop -> [preframe] [kernel] [postframe]
@@ -299,7 +231,7 @@ function testECS() {
         name: 'set_xpos',
         actions: [
             {
-                text: SET_XPOS, event: 'preframe', select: 'each', query: {
+                text: SET_XPOS, event: 'preframe', select: 'foreach', query: {
                     include: ['sprite', 'xpos']
                 },
             },
@@ -314,29 +246,6 @@ function testECS() {
                 emits: ['preframe', 'kernel', 'postframe'] }
         ]
     })
-    em.defineSystem({
-        name: 'joyread',
-        tempbytes: 1,
-        actions: [
-            { text: TEMPLATE2_a, event: 'postframe', select: 'once', query: { include: ['player'] } },
-            { text: TEMPLATE2_b, event: 'postframe', select: 'each', query: { include: ['player'] },
-                emits: ['joyup', 'joydown', 'joyleft', 'joyright', 'joybutton'] }
-        ]
-    });
-    em.defineSystem({
-        name: 'move_x',
-        actions: [
-            { text: TEMPLATE3_L, event: 'joyleft', select: 'source', query: { include: ['player', 'xpos'] }, },
-            { text: TEMPLATE3_R, event: 'joyright', select: 'source', query: { include: ['player', 'xpos'] }, },
-        ]
-    });
-    em.defineSystem({
-        name: 'move_y',
-        actions: [
-            { text: TEMPLATE3_U, event: 'joyup', select: 'source', query: { include: ['player', 'ypos'] } },
-            { text: TEMPLATE3_D, event: 'joydown', select: 'source', query: { include: ['player', 'ypos'] } },
-        ]
-    });
     em.defineSystem({
         name: 'SetHorizPos',
         actions: [