Exidy 440 Board Conversion

mjenison

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Hi all,

I know traditionally people have said that the Exidy 440 boards can't have their roms swapped due to board changes.

However, I was looking at the MAME source and it seems the hardware changes needed to make one Exidy 440 boardset into another may already be well documented...

http://mamedev.org/source/src/mame/drivers/exidy440.c.html

This post here seems to confirm that it is possible:

http://www.gamesforum.ca/showthread.php?t=7485

So, looks like, for most cases, chips just need to be swapped out:

74LS244->74LS240 (18J main board)
74LS367->74LS368 (1A audio board)
74LS128-> ? (74LS32?) (2A audio board)

I'll check my Showdown PCB to what chips I have at these locations.

If you have an Exidy 440 PCB, please post what chips you have at these locations, and any mods that might implement the other changes mentioned in the mame source.
 
Showdown version 4.0 PCB

Audio board:
Loc 1A: 74LS368
Loc 2A: 74LS125
Blue wire: 3B pin 12 to 5A pin 5

Logic board:
Loc 18J: 74LS240
Blue wire: 21A pin 11 to 9K pin 3
Mame mentions "PLD at 1E". Mine has no such chip (empty 28 pin socket). However, there is a 24 pin chip at 11B that has had its markings ground off. Its labeled like one of the regular eproms, but noticed it was different than the 2764s when I went to dump the EPROM data.

Only EPROM 1A is different than Showdown version 5. However, dropping the ROMs in MAME, which emulates Showdown version 5 causes the game to report the following error upon bootup:
Replace P/N 23-0139-01
Location B-11 Logic
 
Showdown roms

Do you have the custom chip pictured here on your board?

sdown440roms.jpg



I do not know its location on the board.



..
 
Do you have the custom chip pictured here on your board?

So THAT'S the mystery chip that MAME is talking about that goes at location 1E.

The answer is NO, my set does NOT have that chip. Do you have any chips labeled with a location of 11-B? It would be a 24pin chip, not a 28-pin (2764).
 
I am going to guess and say yes but I will confirm that tomorrow at the shop.

MSG me if I forget.
 
No 11-B. I do have chips labeled 11-C,11-D, and 11-E.

I do not know if this set of roms is complete. They came in a bag as extra parts with another 440 board I purchased. I may have a complete Showdown pcb. I will dig around for it if needed.
lmk
 
Chiller PCB

Audio board:
Loc 1A: 74LS368
Loc 2A: 74LS125, trace to pin 5 cut, pin 5 jumpered to pin 7
Blue wire: 3B pin 12 to 5A pin 5

Logic board:
Loc 18J: 74LS240
Blue wire: 21A pin 11 to 9K pin 3

Who Dunnit PCB

Audio board:
Loc 1A: 74LS368
Loc 2A: 74LS125, trace to pin 5 cut, pin 5 jumpered to pin 7
Blue wire: 3B pin 12 to 5A pin 5

Logic board:
Loc 18J: 74LS240
Blue wire: 21A pin 11 to 9K pin 3

Crossbow PCB

Audio board:
Loc 1A: 74LS367
Loc 2A: 74LS125
Blue wire: 3B pin 12 to 5A pin 5

Logic board:
Loc 18J: 74LS244

Combat PCB

Audio board:
Loc 1A: 74LS368
Loc 2A: 74LS125

Logic board:
Loc 18J: 74LS240
 
Chiller PCB

Audio board:
Loc 1A: 74LS368
Loc 2A: 74LS125, trace to pin 5 cut, pin 5 jumpered to pin 7
Blue wire: 3B pin 12 to 5A pin 5

Logic board:
Loc 18J: 74LS240
Blue wire: 21A pin 11 to 9K pin 3

Who Dunnit PCB

Audio board:
Loc 1A: 74LS368
Loc 2A: 74LS125, trace to pin 5 cut, pin 5 jumpered to pin 7
Blue wire: 3B pin 12 to 5A pin 5

Logic board:
Loc 18J: 74LS240
Blue wire: 21A pin 11 to 9K pin 3

Crossbow PCB

Audio board:
Loc 1A: 74LS367
Loc 2A: 74LS125
Blue wire: 3B pin 12 to 5A pin 5

Logic board:
Loc 18J: 74LS244

Combat PCB

Audio board:
Loc 1A: 74LS368
Loc 2A: 74LS125

Logic board:
Loc 18J: 74LS240

Just so all of the information is in one place for future readers:

Cheyenne PCB

Audio board:
Loc 1A: 74LS367
Loc 2A: 74LS125
Blue wire: 3B pin 12 to 5A pin 5

Logic board:
Loc 18J: 74LS240
Blue wire: 9K pin 3 to 21A pin 11

(and I can confirm that if you have a working Cheyenne PCB, you can turn it into a working Crossbow PCB by correcting the differences noted above.)

EDIT: Note that the Cheyenne logic board blue wire from 9K pin 3 to 21A pin 11 appears to be redundant. Removal of the jumper still maintains conductivity between the two listed pins, as per the Cheyenne and Crossbow schematics. The purpose of the Cheyenne logic board jumper is therefore not known at this time.
 
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Good information... Just to clarify:

Swapping a 74ls244 with a 74ls240 inverts the 8 outputs (4-bank dip switches, vblank irq, etc)

Swapping a 74ls367 with a 74ls368 inverts the 6 outputs (This is the control inputs)

74LS125 is a tri-state buffer and 74LS32 is a NOR gate, so I'd need to look at the schems to see how the gates are being used to comment on the change.
The jumper disables coin3, and probably intentionally causes the jammed message on games that look for a 3rd coin slot.

21A:11 to 9K:3 is shown as wired in the Crossbow schematics... dunno why it'd need a jumper unless it was cut for another board.

Looks like most of these changes could be worked around in code to make any ROM run on any board.
 
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I've learned to take the Exidy schematics as more like guidelines...the Cheyenne manual / schematics also says that 18J is a 74LS244, when it is really a 74LS240. Both Cheyenne and Crossbow schematics also state that 12H is a 74S287 when it's really an 82S129 PROM.

I finally found hi-res images of 3 different Crossbow pcb's, and none showed the 21A:11 to 9K:3 jumper, and every Cheyenne image I could find did have the jumper. So I removed it. I did not test with it in place once the board was a Crossbow, but I will do that tonight. I'll ring out the board first to see if that trace is indeed intact. I can say that the board I started with was an original Cheyenne board, and had no mods done to it. It is possible that the Cheyenne jumper was an Engineering Change wire (for redundancy?) and not part of a protection scheme. I'll let you know what I find out.

My intent was to make a true original dedicated Crossbow board from a Cheyenne, so I was worried about the hardware only, and not a software workaround...but I agree, from what I see so far the copy protection is pretty trivial once documented, and can likely be tweaked in ROMs to make swaps easier. Heck, it must be possible as it has to be a method used by the Collex'n kit.
 
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I can confirm that the 21A:11 to 9K:3 jumper seems to have no effect on Crossbow's ability to boot, pass self-test, and enter attract mode.

That is because, with the jumper removed, there is still continuity from 21A:11 to 9K:3. This is per the schematics as HudsonArcade mentioned. Therefore, this jumper appears to be redundant. It's purpose is not known at this time. I have reinstalled it for now, and edited my post on the previous page.
 
I've learned to take the Exidy schematics as more like guidelines...the Cheyenne manual / schematics also says that 18J is a 74LS244, when it is really a 74LS240. Both Cheyenne and Crossbow schematics also state that 12H is a 74LS287 when it's really an 82S129 PROM.

74S287 and 82S129 are both 256x4 tri-state proms, so that's not really a "difference"
 
I can confirm that the 21A:11 to 9K:3 jumper seems to have no effect on Crossbow's ability to boot, pass self-test, and enter attract mode.

That is because, with the jumper removed, there is still continuity from 21A:11 to 9K:3. This is per the schematics as HudsonArcade mentioned. Therefore, this jumper appears to be redundant. It's purpose is not known at this time. I have reinstalled it for now, and edited my post on the previous page.

I's possible that trace was cut as "protection" on some other version of the hardware.
 
Agreed (and embarrassed that I forgot those PROMs were effectively the same). Still interesting about the jumper. Cheyenne was the next game out after Crossbow, right? I'm trying to think of a scenario where they would have had a chance to break the trace and "cash in" on it from a copy protection benefit.

Unless they started adding the jumper in the build process for Cheyenne and/or Crossbow (even though it was redundant for those games), prior to then cutting the trace for all subsequent games so that the protection scheme was implementable by either the presence or lack of the jumper? Maybe we'd find the trace cut on a Combat board...since it looks like Combat does not have the jumper but it's back for Chiller and Who Dunnit, for example (per mjenison's earlier posts in this thread).
 
I've got a working Crackshot PCB that has all the mods, both jumper and chip wise, for Chiller. Burned the EPROMs for both vid and sound, and get a HARDWARE DOWN: ERROR 0 message.

No info here on the Crackshot PCB but it appeared, based on the critical chips and jumpers for Chiller, to be a drop-in replacement.

Anyone with further info on Crackshot? No manual that I can find, either.
 
I don't know anything about Crackshot, but the MAME driver says this for Crackshot and Chiller (both relative to a Crossbow base):
Code:
 Differences between machines (assuming Crossbow is the base)

    Crackshot (reports Hardware Error W if any of these are not true)
        * a read from $2E20 must return 0 in bit 2
        * a read from $2E80 must return 0's in bits 1,2,3,4,5
        * a read from $2B03 must return 0 in bit 0
        conclusion: LS244 at 18J on main board needs to generate negative logic
                        LS367 at 1A on audio board needs to generate negative logic
                        LS128 at 2A on audio board needs negative logic into pin 5

    Chiller (reports Hardware Error R if any of these are not true)
        * a read from $2E20 must return 0 in bit 2
        * a read from $2E80 must return 0's in bits 1,2,3,4,5
        * a read from $2B03 must return 0 in bit 0
        conclusion: LS244 at 18J on main board needs to generate negative logic
                        LS367 at 1A on audio board needs to generate negative logic
                        LS128 at 2A on audio board needs negative logic into pin 5

...which likely doesn't help, as is seems to state that the configuration of Crackshot and Chiller should be the same. Maybe there's a unique jumper or cut trace for Crackshot. Sorry I'm just guessing...I'm not anywhere where I can access the schematics or a board at the moment. Do you know if the HARDWARE DOWN: ERROR 0 that you are seeing means something else specific compared to the Hardware Error W & R that are in the MAME notes?
 
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