diff --git a/Makefile b/Makefile
index 55a73ac..f6d44ed 100644
--- a/Makefile
+++ b/Makefile
@@ -45,8 +45,13 @@ bin/driver.bin: bin obj/driver.o
 	$(OBJCOPY) -O binary obj/driver.o $@
 
 
-bin/rom.bin: baserom.bin RDisk1M5.dsk bin bin/driver.bin obj/entry_rel.sym 
-	cp baserom.bin $@ # copy base rom
+bin/rom.bin: baserom.bin RDisk1M5.dsk bin bin/driver.bin obj/driver_abs.sym obj/entry_rel.sym 
+	cp baserom.bin $@ # Copy base rom
+	# Patch boot
+	printf '\x4E' | dd of=$@ bs=1 seek=5888 count=1 conv=notrunc # Copy JSR opcode into IsFloppy boot routine
+	printf '\xF9' | dd of=$@ bs=1 seek=5889 count=1 conv=notrunc # Copy JSR opcode second byte
+	cat obj/driver_abs.sym | grep "BootCheckEntry" | cut -c1-8 | xxd -r -p - | dd of=$@ bs=1 seek=5890 count=4 conv=notrunc
+	# Patch driver
 	dd if=bin/driver.bin of=$@ bs=1 seek=335248 skip=32 conv=notrunc # Copy driver code
 	printf '\x78' | dd of=$@ bs=1 seek=335168 count=1 conv=notrunc # Set resource flags
 	printf '\x4F' | dd of=$@ bs=1 seek=335216 count=1 conv=notrunc # Set driver flags
diff --git a/bin/driver.bin b/bin/driver.bin
index fb6f22e..d03cd03 100755
Binary files a/bin/driver.bin and b/bin/driver.bin differ
diff --git a/bin/rom.bin b/bin/rom.bin
index 15d5f6d..6a06eff 100755
Binary files a/bin/rom.bin and b/bin/rom.bin differ
diff --git a/entry.s b/entry.s
index 57206af..d8caacc 100644
--- a/entry.s
+++ b/entry.s
@@ -1,51 +1,65 @@
+.EQU	killCode,	 1
+.EQU	noQueueBit,	 9
+.EQU	kioTrap,	 6
+.EQU	kioResult,	16
+.EQU	kcsCode,	26
+.EQU	JIODone,	0x08FC
+
 dc.l	0x00000000, 0x00000000, 0x00000000, 0x00000000
 dc.l	0x00000000, 0x00000000, 0x00000000, 0x00000000
 .ascii	"\9GWROMDisk\0"
 .align 4
 
-.EQU	killCode,	 1
-.EQU	noQueueBit,	 9
-
-.EQU	kioTrap,	 6
-.EQU	kioResult,	16
-.EQU	kcsCode,	26
-
-.EQU	JIODone,	0x08FC
+BootCheckEntry:
+	* Boot if reference number == -5
+	cmp 		#-5, 8(%A2)
+	beq.b 		BootCheckRet
+	* Otherwise don't boot if reference number != -50
+	cmp			#-50, 8(%A2)
+	bne.b		BootCheckRet
+	* Call to check PRAM
+	movem.l		%A0-%A7/%D0-%D7, -(%SP)
+	jsr			RDiskBootCheckPRAM
+	cmp			#0, %D0
+	movem.l		(%SP)+, %A0-%A7/%D0-%D7
+BootCheckRet:
+	rts
+	jmp BootCheckEntry
 
 DOpen:
-	movem.l		%A0-%A1,-(%SP)
+	movem.l		%A0-%A1, -(%SP)
 	bsr			RDiskOpen
-	movem.l		(%SP)+,%A0-%A1
+	movem.l		(%SP)+, %A0-%A1
 	rts
 
 DClose:
-	movem.l		%A0-%A1,-(%SP)
+	movem.l		%A0-%A1, -(%SP)
 	bsr			RDiskClose
-	movem.l		(%SP)+,%A0-%A1
+	movem.l		(%SP)+, %A0-%A1
 	rts
 
 DPrime:
-	movem.l		%A0-%A1,-(%SP)
+	movem.l		%A0-%A1, -(%SP)
 	bsr			RDiskPrime
-	movem.l		(%SP)+,%A0-%A1
+	movem.l		(%SP)+, %A0-%A1
 	bra.b		IOReturn
 
 DControl:
-	movem.l		%A0-%A1,-(%SP)
+	movem.l		%A0-%A1, -(%SP)
 	bsr			RDiskControl
-	movem.l		(%SP)+,%A0-%A1
+	movem.l		(%SP)+, %A0-%A1
 	cmpi.w		#killCode, kcsCode(%A0)
 	bne.b		IOReturn
 	rts
 
 DStatus:
-	movem.l		%A0-%A1,-(%SP)
+	movem.l		%A0-%A1, -(%SP)
 	bsr			RDiskStatus
-	movem.l		(%SP)+,%A0-%A1
+	movem.l		(%SP)+, %A0-%A1
 
 IOReturn:
-	move.w		kioTrap(%A0),%D1
-	btst		#noQueueBit,%D1
+	move.w		kioTrap(%A0), %D1
+	btst		#noQueueBit, %D1
 	beq.b		Queued
 
 NotQueued:
@@ -54,7 +68,7 @@ NotQueued:
 	clr.w		%D0
 
 ImmedRTS:
-	move.w		%D0,kioResult(%A0)
+	move.w		%D0, kioResult(%A0)
 	rts
 
 Queued:
@@ -64,5 +78,5 @@ Queued:
 	rts
 
 MyIODone:
-	move.l		JIODone,-(%SP)
+	move.l		JIODone, -(%SP)
 	rts
diff --git a/rdisk.c b/rdisk.c
index ba9b783..106cc7b 100644
--- a/rdisk.c
+++ b/rdisk.c
@@ -78,6 +78,13 @@ const long RDiskIcon[65] = {
 	0
 };
 
+#pragma parameter __D0 RDiskBootCheckPRAM()
+short RDiskBootCheckPRAM() {
+	char mount;
+	RDiskReadXPRAM(1, 4, &mount);
+	return mount == 0x5D;
+}
+
 // Switch to 24-bit mode and copy
 void RDiskCopy24(Ptr sourcePtr, Ptr destPtr, unsigned long byteCount) {
 	char mode = true32b;
@@ -116,7 +123,9 @@ OSErr RDiskOpen(IOParamPtr p, DCtlPtr d) {
 	c = *(RDiskStorage_t**)d->dCtlStorage;
 
 	// Initialize storage struct fields
-	c->init_done = 0;
+	c->initialized = 0;
+	c->offline = 0;
+	c->forceMount = 0;
 	c->ramdisk = NULL;
 	c->copy24 = (RDiskCopy_t)copy24;
 
@@ -138,22 +147,22 @@ OSErr RDiskOpen(IOParamPtr p, DCtlPtr d) {
 	return noErr;
 }
 
-OSErr RDiskInit(IOParamPtr p, DCtlPtr d, RDiskStorage_t *c) {
-	char startup = 0, ram = 0;
+static OSErr RDiskInit(IOParamPtr p, DCtlPtr d, RDiskStorage_t *c) {
+	char mount = 0, ram = 0;
 
 	// Mark init done
-	c->init_done = 1;
+	c->initialized = 1;
 
 	// Read PRAM
-	RDiskReadXPRAM(1, 4, &startup);
+	RDiskReadXPRAM(1, 4, &mount);
 	RDiskReadXPRAM(1, 5, &ram);
 
 	// Either enable ROM disk or remove ourselves from the drive queue
-	if (startup || RDiskIsRPressed()) { // If ROM disk boot set in PRAM or R pressed,*/
+	if (c->forceMount || mount || RDiskIsRPressed()) { // If ROM disk boot set in PRAM or R pressed,
 		// Set ROM disk attributes
 		c->status.writeProt = -1; // Set write protected
 		// If RAM disk set in PRAM or A pressed, enable RAM disk
-		if (ram || RDiskIsAPressed() || c->mount) { 
+		if (ram || RDiskIsAPressed()) { // If RAM disk set in PRAM or A pressed
 			// Try to allocate RAM disk buffer
 			if (*MMU32bit) { // 32-bit mode
 				unsigned long minBufPtr, newBufPtr;
@@ -161,7 +170,7 @@ OSErr RDiskInit(IOParamPtr p, DCtlPtr d, RDiskStorage_t *c) {
 				minBufPtr = ((unsigned long)*MemTop / 2) + 1024;
 				newBufPtr = (unsigned long)*BufPtr - RDiskSize;	
 				if (newBufPtr > minBufPtr && (unsigned long)*BufPtr > newBufPtr) {
-					// Allocate RAM disk buffer by lowering BufPtrå			
+					// Allocate RAM disk buffer by lowering BufPtra
 					*BufPtr = (Ptr)newBufPtr;
 					// Set RAM disk buffer pointer.
 					c->ramdisk = *BufPtr;
@@ -200,9 +209,8 @@ OSErr RDiskInit(IOParamPtr p, DCtlPtr d, RDiskStorage_t *c) {
 		// If we found our driver, remove it from the queue
 		if (dq->dQRefNum == d->dCtlRefNum) {
 			Dequeue((QElemPtr)dq, head);
-			DisposeHandle(d->dCtlStorage);
 		}
-		d->dCtlStorage = NULL;
+		c->offline = 1;
 		// Return disk offline error
 		return offLinErr;
 	}
@@ -219,9 +227,11 @@ OSErr RDiskPrime(IOParamPtr p, DCtlPtr d) {
 	if (!d->dCtlStorage) { return offLinErr; }
 	// Dereference dCtlStorage to get pointer to our context
 	c = *(RDiskStorage_t**)d->dCtlStorage;
+	// Return disk offline error if marked offline
+	if (c->offline) { return offLinErr; }
 
 	// Initialize if this is the first prime call
-	if (!c->init_done) { 
+	if (!c->initialized) { 
 		OSErr ret = RDiskInit(p, d, c);
 		if (ret != noErr) { return ret; }
 	}
@@ -291,7 +301,7 @@ OSErr RDiskControl(CntrlParamPtr p, DCtlPtr d) {
 		case 21: case 22:
 			*(Ptr*)&p->csParam = (Ptr)&RDiskIcon;
 			return noErr;
-		case 128: c->mount = 1; return noErr;
+		case 128: c->forceMount = 1; return noErr;
 		default: return controlErr;
 	}
 }
@@ -303,6 +313,8 @@ OSErr RDiskStatus(CntrlParamPtr p, DCtlPtr d) {
 	if (!d->dCtlStorage) { return statusErr; }
 	// Dereference dCtlStorage to get pointer to our context
 	c = *(RDiskStorage_t**)d->dCtlStorage;
+	// Fail if offline
+	if (c->offline) { return statusErr; }
 	// Handle status request based on csCode
 	switch (p->csCode) {
 		case drvStsCode:
diff --git a/rdisk.h b/rdisk.h
index b0ae4d5..29b2fff 100644
--- a/rdisk.h
+++ b/rdisk.h
@@ -37,10 +37,11 @@ typedef void (*RDiskCopy_t)(Ptr, Ptr, unsigned long);
 
 typedef struct RDiskStorage_s {
 	DrvSts2 status;
-	unsigned long init_done;
+	char initialized;
+	char offline;
+	char forceMount;
 	char *ramdisk;
 	RDiskCopy_t copy24;
-	char mount;
 } RDiskStorage_t;
 
 #endif