I've tried the SoMI patch and kept getting divide errors. The solution I use for making these games work under MS-DOS is by using a utility called Setmul. You can use Setmul to disable the L1 Cache of your CPU which will slow things down enough to let you play these games properly.

You can also use a program called MySlow under Windows 9x which will also allow you to play them without having to boot into DOS.

I will give setmul a try but I am not sure it works with K5, we will see..

Setmul L1d worked like a charm!

Glad to hear it! The only situation where Setmul has given me problems is when I’m using a USB mouse in DOS using the USBMOUSE TSR.

appiah4 wrote on 2020-02-09, 08:39:

I will give setmul a try but I am not sure it works with K5, we will see..

I also thought these slow-down utilities which can disable caches only work on certain processors....maybe I should try it on my P3 700mhz (which has zero hardware slowdown/BIOS-enabled type stuff from what I can see on my 440bx MB's bios).

Also, BTW, I'm still able to play Monkey Island 1 and 2 at the seemingly correct speed on my P3 - I didn't patch the .EXE or anything. (I've tried them both through Win98, and exiting to pure DOS mode as well).

The divide error in Indy 3 and Monkey 1 are part of the AdLib-related code. There are no other CPU speed related issues in the code that I'm aware of. If you force these games into pure PC Speaker mode by running them with the "i" parameter, the games should work perfectly fine regardless of the CPU speed.

Later releases of Monkey 1 don't have that divide error and I think that by the time Monkey 2 came out the problem in the AdLib code was fixed for good.

It's possible to apply a custom patch to the executable that fixes the divide error. I've created such a patch for the EGA version of Monkey 1 last year. And I think I also created patches for the VGA floppy versions of Indy 3 and Monkey 1. If you want to create fully fixed executables for these games so that you don't have to rely on slowdown utilities anymore, let me know.

I'd be more than happy to have fully patched executables for INDY256 and MONKEY (VGA) 😀

Monkey2 has no problems, as you pointed out. I haven't tried LOOM out but that will probably also have issues..

These are the patches for the versions available to me. Just run the game with the "?" parameter and it should tell you the version number.

• Monkey 1 EGA (versions 4.0.62 and 4.0.64)
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  1#----------------------------------------
  2# patches for Interpreter Version 4.0.62
  3#----------------------------------------
  4
  5%exefile monkey.exe 116209
  6
  7#avoid the divide error (this may cause timing issues with AdLib music):
  8%patch $125F7
  9	$B1 $03		#	mov	cl, 3
  10	$D3 $E8		#	shr	ax, cl
  11	$90 $90		#	nop nop
  12
  13#avoid timing issues with the AdLib music:
  14%patch $12DAE
  15	$50		#	push	ax
  16	$86 $E0		#	xchg	al, ah
  17	$BA $0388w	#	mov	dx, 388h
  18	$EE		#	out	dx, al
  19	$B9 6w		#	mov	cx, 6
  20	$EC		#l1:	in	dx, al
  21	$E2 $FD		#	loop	l1
  22	$86 $E0		#	xchg	al, ah
  23	$42		#	inc	dx
  24	$EE		#	out	dx, al
  25	$4A		#	dec	dx
  26	$B9 35w		#	mov	cx, 35
  27	$EC		#l2:	in	al, dx
  28	$E2 $FD		#	loop	l2
  29	$58		#	pop	ax
  30	$90		#	nop
  31
  32#fix timing issues in AdLib detection code:
  33%patch $132CA		#cs:3D0A
  34	$53		#	push	bx
  35	$51		#	push	cx
  36	$B8 $0100w	#	mov	ax, 100h
  37	$E8 $FAD1w	#	call	AL_Out		(at cs:37E3)
  38	$B8 $0460w	#	mov	ax, 460h
  39	$E8 $FACBw	#	call	AL_Out
  40	$B8 $0480w	#	mov	ax, 480h
  41	$E8 $FAC5w	#	call	AL_Out
  42	$BA $0388w	#	mov	dx, 388h
  43	$EC		#	in	al, dx
  44	$88 $C3		#	mov	bl, al
  45	$B8 $02FFw	#	mov	ax, 2FFh
  46	$E8 $FAB9w	#	call	AL_Out
  47	$B8 $0421w	#	mov	ax, 421h
  48	$E8 $FAB3w	#	call	AL_Out
  49	$B9 100w	#	mov	cx, 100
  50	$EC		#l1:	in	al, dx
  51	$E2 $FD		#	loop	l1
  52	$88 $C7		#	mov	bh, al
  53	$B8 $0460w	#	mov	ax, 460h
  54	$E8 $FAA5w	#	call	AL_Out
  55	$B8 $0480w	#	mov	ax, 480h
  56	$E8 $FA9Fw	#	call	AL_Out
  57	$33 $C0		#	xor	ax, ax
  58	$F6 $C3 $E0	#	test	bl, 0E0h
  59	$75 $0A		#	jnz	nope
  60	$80 $E7 $E0	#	and	bh, 0E0h
  

  …Show last 90 lines

  61	$80 $FF $C0	#	cmp	bh, 0C0h
  62	$75 $02		#	jne	nope
  63	$B0 $01		#	mov	al, 1
  64	$59		#nope:	pop	cx
  65	$5B		#	pop	bx
  66	$1F		#	pop	ds
  67	$CB		#	retf
  68	
  69#disable GameBlaster detection:
  70%patch $120BF
  71	$33 $C0		#	xor	ax, ax
  72	$CB		#	retf
  73
  74
  75#----------------------------------------
  76# patches for Interpreter Version 4.0.64
  77#----------------------------------------
  78
  79%exefile monkey.exe 115357
  80
  81#avoid the divide error (this may cause timing issues with AdLib music):
  82%patch $12487
  83	$B1 $03		#	mov	cl, 3
  84	$D3 $E8		#	shr	ax, cl
  85	$90 $90		#	nop nop
  86
  87#avoid timing issues with the AdLib music:
  88%patch $12C3E
  89	$50		#	push	ax
  90	$86 $E0		#	xchg	al, ah
  91	$BA $0388w	#	mov	dx, 388h
  92	$EE		#	out	dx, al
  93	$B9 6w		#	mov	cx, 6
  94	$EC		#l1:	in	dx, al
  95	$E2 $FD		#	loop	l1
  96	$86 $E0		#	xchg	al, ah
  97	$42		#	inc	dx
  98	$EE		#	out	dx, al
  99	$4A		#	dec	dx
  100	$B9 35w		#	mov	cx, 35
  101	$EC		#l2:	in	al, dx
  102	$E2 $FD		#	loop	l2
  103	$58		#	pop	ax
  104	$90		#	nop
  105
  106#fix timing issues in AdLib detection code:
  107%patch $1315A		#cs:3B5A
  108	$53		#	push	bx
  109	$51		#	push	cx
  110	$B8 $0100w	#	mov	ax, 100h
  111	$E8 $FAD1w	#	call	AL_Out		(at cs:3633)
  112	$B8 $0460w	#	mov	ax, 460h
  113	$E8 $FACBw	#	call	AL_Out
  114	$B8 $0480w	#	mov	ax, 480h
  115	$E8 $FAC5w	#	call	AL_Out
  116	$BA $0388w	#	mov	dx, 388h
  117	$EC		#	in	al, dx
  118	$88 $C3		#	mov	bl, al
  119	$B8 $02FFw	#	mov	ax, 2FFh
  120	$E8 $FAB9w	#	call	AL_Out
  121	$B8 $0421w	#	mov	ax, 421h
  122	$E8 $FAB3w	#	call	AL_Out
  123	$B9 100w	#	mov	cx, 100
  124	$EC		#l1:	in	al, dx
  125	$E2 $FD		#	loop	l1
  126	$88 $C7		#	mov	bh, al
  127	$B8 $0460w	#	mov	ax, 460h
  128	$E8 $FAA5w	#	call	AL_Out
  129	$B8 $0480w	#	mov	ax, 480h
  130	$E8 $FA9Fw	#	call	AL_Out
  131	$33 $C0		#	xor	ax, ax
  132	$F6 $C3 $E0	#	test	bl, 0E0h
  133	$75 $0A		#	jnz	nope
  134	$80 $E7 $E0	#	and	bh, 0E0h
  135	$80 $FF $C0	#	cmp	bh, 0C0h
  136	$75 $02		#	jne	nope
  137	$B0 $01		#	mov	al, 1
  138	$59		#nope:	pop	cx
  139	$5B		#	pop	bx
  140	$1F		#	pop	ds
  141	$CB		#	retf
  142
  143#disable GameBlaster detection:
  144%patch $11F54
  145	$33 $C0		#	xor	ax, ax
  146	$CB		#	retf
  147
  148
  149%end
  

• Monkey 1 VGA (version 5.0.18)
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  1%exefile monkey.exe 111817
  2%patch $12A2A $72
  3%end
  

• Monkey 1 VGA (version 5.0.19)
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  1%exefile monkey.exe 112107
  2%patch $12B5A $72
  3%end
  

• Indy 3 VGA (version 3.0.22 and 3.0.23)
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  1%exefile indy256.exe 108124
  2%patch $1E3A $72
  3%end
  

• Loom VGA CD (version 5.1.42)
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  1%exefile loom.exe 114529
  2%patch $126EA $72
  3%end
  

My copy of Loom EGA (version 3.5.37) doesn't have the problem with the divide eror.

Monkey 1 VGA and Indy 3 VGA are basically 1-byte fixes, the fixes for Monkey 1 EGA are a bit more complicated. If you have a different version, I would need you to send me the executables.

Edit: corrected the patches for Monkey 1 VGA and Indy 3 and added Loom VGA/CD as well as another version of Monkey 1 VGA
Edit 2: corrected the version number for Loom

Just wanted to say that the patches you posted work wonderfully for Monkey Island EGA. No more divide error!