diff --git a/src/common/baseplatform.ts b/src/common/baseplatform.ts
index 2fced0af..e80ecaf8 100644
--- a/src/common/baseplatform.ts
+++ b/src/common/baseplatform.ts
@@ -85,7 +85,7 @@ export interface Platform {
   getPresets?(): Preset[];
   pause(): void;
   resume(): void;
-  loadROM(title: string, rom: any); // TODO: Uint8Array
+  loadROM(title: string, rom: any, origin?: number); // TODO: Uint8Array
   loadBIOS?(title: string, rom: Uint8Array);
   getROMExtension?(rom: FileData): string;
 
@@ -869,8 +869,8 @@ export abstract class BaseMachinePlatform<T extends Machine> extends BaseDebugPl
     }
   }
 
-  loadROM(title, data) {
-    this.machine.loadROM(data, title);
+  loadROM(title, data, origin?: number) {
+    this.machine.loadROM(data, title, origin);
     this.reset();
   }
 
diff --git a/src/common/devices.ts b/src/common/devices.ts
index d22848fe..70485c44 100644
--- a/src/common/devices.ts
+++ b/src/common/devices.ts
@@ -68,7 +68,7 @@ export interface SampledAudioSource {
 }
 
 export interface AcceptsROM {
-  loadROM(data: Uint8Array, title?: string): void;
+  loadROM(data: Uint8Array, title?: string, origin?: number): void;
 }
 
 export interface AcceptsBIOS {
@@ -247,7 +247,7 @@ export abstract class BasicHeadlessMachine implements HasCPU, Bus, AcceptsROM, P
   reset() {
     this.cpu.reset();
   }
-  loadROM(data: Uint8Array, title?: string): void {
+  loadROM(data: Uint8Array, title?: string, origin?: number): void {
     if (!this.rom) this.rom = new Uint8Array(this.defaultROMSize);
     if (data.length > this.rom.length)
       throw new Error(`ROM too big: ${data.length} > ${this.rom.length}`);
diff --git a/src/common/workertypes.ts b/src/common/workertypes.ts
index 8950af99..a7c5b78e 100644
--- a/src/common/workertypes.ts
+++ b/src/common/workertypes.ts
@@ -147,6 +147,7 @@ export interface WorkerOutputResult<T> {
   params?: {}
   segments?: Segment[]
   debuginfo?: {} // optional info
+  origin?: number
 }
 
 export function isUnchanged(result: WorkerResult) : result is WorkerUnchangedResult {
diff --git a/src/ide/ui.ts b/src/ide/ui.ts
index 193da4ce..2f2b85f5 100644
--- a/src/ide/ui.ts
+++ b/src/ide/ui.ts
@@ -931,7 +931,7 @@ async function setCompileOutput(data: WorkerResult) {
       try {
         clearBreakpoint(); // so we can replace memory (TODO: change toolbar btn)
         _resetRecording();
-        await platform.loadROM(getCurrentPresetTitle(), rom);
+        await platform.loadROM(getCurrentPresetTitle(), rom, data.origin);
         current_output = rom;
         if (!userPaused) _resume();
         writeOutputROMFile();
diff --git a/src/machine/apple2.ts b/src/machine/apple2.ts
index 75a35b6f..33d8dcff 100644
--- a/src/machine/apple2.ts
+++ b/src/machine/apple2.ts
@@ -166,7 +166,7 @@ export class AppleII extends BasicScanlineMachine implements AcceptsBIOS {
       }
       this.bios = Uint8Array.from(data);
    }
-   loadROM(data) {
+   loadROM(data, title?, origin?: number) {
       // is it a 16-sector 35-track disk image?
       if (data.length == 16 * 35 * 256) {
          var diskii = new DiskII(this, data);
@@ -181,17 +181,17 @@ export class AppleII extends BasicScanlineMachine implements AcceptsBIOS {
             this.HDR_SIZE = 58;
          } else {
             // 4-byte DOS header? (TODO: hacky detection)
-            const origin = this.rom[0] | (this.rom[1] << 8);
+            const hdrOrigin = this.rom[0] | (this.rom[1] << 8);
             const size = this.rom[2] | (this.rom[3] << 8);
-            let isPlausible = origin < 0xc000
-               && origin + size < 0x13000
-               && (origin == 0x803 || (origin & 0xff) == 0);
+            let isPlausible = hdrOrigin < 0xc000
+               && hdrOrigin + size < 0x13000
+               && (hdrOrigin == 0x803 || (hdrOrigin & 0xff) == 0);
             if (size == data.length - 4 && isPlausible) {
-               this.LOAD_BASE = origin;
+               this.LOAD_BASE = hdrOrigin;
                this.HDR_SIZE = 4;
             } else {
-               // default = raw binary @ $803
-               this.LOAD_BASE = 0x803;
+               // Load @ specified origin, fallback to $803
+               this.LOAD_BASE = origin ?? 0x803;
                this.HDR_SIZE = 0;
             }
          }
diff --git a/src/worker/tools/dasm.ts b/src/worker/tools/dasm.ts
index 5a4cc9ad..96fc2d86 100644
--- a/src/worker/tools/dasm.ts
+++ b/src/worker/tools/dasm.ts
@@ -133,6 +133,24 @@ function parseSymbolMap(asym: string) {
     return symbolmap;
 }
 
+// Determine likely origin address from listing
+function getMinListingOffset(listings: CodeListingMap): number | undefined {
+    let minOffset: number | undefined;
+    for (let key in listings) {
+        let lst = listings[key];
+        if (lst && lst.lines) {
+            for (let line of lst.lines) {
+                if (line.iscode && line.offset > 0) {
+                    if (minOffset === undefined || line.offset < minOffset) {
+                        minOffset = line.offset;
+                    }
+                }
+            }
+        }
+    }
+    return minOffset;
+}
+
 export function assembleDASM(step: BuildStep): BuildStepResult {
     load("dasm");
     var unresolved = {};
@@ -216,6 +234,7 @@ export function assembleDASM(step: BuildStep): BuildStepResult {
         listings: listings,
         errors: errors,
         symbolmap: symbolmap,
+        origin: getMinListingOffset(listings),
     };
 }
 
@@ -268,6 +287,7 @@ export function assembleDASM2(step: BuildStep): BuildStepResult {
         output,
         errors,
         listings,
-        symbolmap
+        symbolmap,
+        origin: getMinListingOffset(listings),
     };
 }