diff --git a/firmware/HDD/a65_w32.exe b/firmware/HDD/a65_w32.exe
deleted file mode 100644
index 5316c33e..00000000
Binary files a/firmware/HDD/a65_w32.exe and /dev/null differ
diff --git a/firmware/HDD/a65v106_w32.zip b/firmware/HDD/a65v106_w32.zip
deleted file mode 100644
index 8793ec91..00000000
Binary files a/firmware/HDD/a65v106_w32.zip and /dev/null differ
diff --git a/firmware/HDD/build.bat b/firmware/HDD/build.bat
index c412496c..c9d47c0a 100644
--- a/firmware/HDD/build.bat
+++ b/firmware/HDD/build.bat
@@ -1,4 +1,11 @@
-a65_w32 -b -l HDDRVR.A65 >hddrvr.lst
-@del HDDRVR.BIN
-rename 6502.bin HDDRVR.BIN
-copy HDDRVR.BIN ..\..\resource
\ No newline at end of file
+@REM ACME only ever returns 0!
+acme.exe hddrvr.a65
+@IF %ERRORLEVEL% NEQ 0 goto error
+
+copy hddrvr.bin ..\..\resource
+@goto end
+
+:error
+@echo "ACME failed"
+
+:end
diff --git a/firmware/HDD/hddrvr.a65 b/firmware/HDD/hddrvr.a65
index d3362df5..fc750587 100644
--- a/firmware/HDD/hddrvr.a65
+++ b/firmware/HDD/hddrvr.a65
@@ -26,14 +26,14 @@
 ;
 
 ; Modified by Tom Charlesworth:
-; . Fixed so it can be assembled by a65 v1.06
+; . Updated so it can be assembled by ACME 0.96.4
 ; . Fixed so that ProDOS entrypoint is $c70a (26 Dev 2007) (Bug #12723)
 ; . Modified to support Apple Oasis' entrypoint: $c761 (8 Sept 2012) (Feature #5557)
 ; . Added support for SmartPort entrypoint (20 Oct 2012)
 ;   - EG. "Prince of Persia (Original 3.5 floppy for IIc+).2mg"
 ; . GH#370 (Robert Hoem, 27 Oct 2016):
-    . Added a check against open-apple during boot to route boot to slot 6
-    . This happens after the first two blocks are loaded from the HD.
+;   . Added a check against open-apple during boot to route boot to slot 6
+;   . This happens after the first two blocks are loaded from the HD.
 ; TODO:
 ; . Make code relocatable (so HDD controller card can go into any slot)
 ; . Remove support for Entrypoint_C746 (old AppleWin) & Entrypoint_C761 (Apple Oasis)
@@ -41,6 +41,10 @@
 ; . Check SmartPort: Is it OK to trash Y and $42,..,$47 ?
 ;
 
+!cpu 6502	; Compatible with all Apple2's
+!to "hddrvr.bin", plain
+!sl "hddrvr.labels"
+
 ; constants
 hd_execute = $c0f0
 hd_error = $c0f1
@@ -65,6 +69,8 @@ BUTTON0 = $C061
 ;; code
 *= $c700	; org $c700
 
+!zone code
+
 start
 
 ; Autoboot and ProDOS look at the following few opcodes to detect block devices
@@ -295,6 +301,8 @@ SmartPort3
 ;======================================
 ; 12 unused bytes
 
+!zone data
+
 ; $CsFE = status bits (BAP p7-14)
 ;  7 = medium is removable
 ;  6 = device is interruptable
@@ -308,12 +316,9 @@ SmartPort3
 ; $D7 = Removable, Interruptable, #Volumes=2, Supports write/read/status
 ; $BF = Removable, Interruptable, #Volumes=4, Supports format/write/read/status (KEGS / IIGS)
 
-
 ; datablock.  This starts near the end of the firmware (at offset $FC)
 ;; data
 *= $c7fc	; org $c7fc
- .word $7fff ; how many blocks are on the device.
- .byte $D7 ; specifics about the device (number of drives, read/write/format capability, etc)
- .byte <Entrypoint_ProDOS ; entry point offset for ProDOS (must be $0a)
-
- .end
+ !word $7fff ; how many blocks are on the device.
+ !byte $D7 ; specifics about the device (number of drives, read/write/format capability, etc)
+ !byte <Entrypoint_ProDOS ; entry point offset for ProDOS (must be $0a)