Switch game versions in one cart

aha2940 · Jul 6, 2014

Hi

I know there are some games (like magician lord and shock troopers) which have different versions, with notorious differences. I also know (from the MAME dumps) that both versions of these games differ only in one chip (P ROM). Is there any way to install both P ROMS inside a cart of these games and being able to choose the version you use with a switch? I was thinking of piggybacking one P chip over the other (one being original, the other EPROM) and then choose which one gets +5V and ground using a switch. Would that work, or would something get fried?

Thanks!!

Niko · Jul 6, 2014

really it would just depend on the ICs but, honestly I wouldnt do it. Just buy the alternate cart or replace the IC with a socket and swap the chips as needed. Either way your going to kill any resale value of the cart.

aha2940 · Jul 6, 2014

Niko49 said:
really it would just depend on the ICs but, honestly I wouldnt do it. Just buy the alternate cart or replace the IC with a socket and swap the chips as needed. Either way your going to kill any resale value of the cart.

I would get both versions, but getting one MVS Magician Lord is hard enough (I have not been able to get even one, I only have it on AES) I can't imagine how hard can be getting two. Also, there is no guarantee that I will get one version or the other, and asking the seller is not always reliable. Finally, being these two $90 or $100 carts (pretty expensive for MVS standards), makes everything more complicated. I do not really care for resale value, I will not resell them, but having both versions in one cart would be nice IMO.

Thanks!!

kuze · Jul 6, 2014

Someone with enough skill could probably make a modded p ROM with a menu to select the different versions. There probably isn't enough desire out there for it though.

JMKurtz · Jul 6, 2014

Yeah, it's pretty simple to do. I did a Puzzle de Pon / Puzzle de Pon R that you could change with a switch many years ago. I think MAS also did a couple that were a little more extreme, like Baseball Stars 2 and Neo Turf Masters, or something like that -- forget what it was though. But they are doable.

Jeff

mikejmoffitt · Jul 6, 2014

Stacking them is fine, but you don't want to switch which gets 5V or not, as that leaves the inputs there which will cause problems. Instead, you want them both powered, and use a switch to control which one's /CE line gets tied high vs gets the original signal. Pulling /CE to 5V will disable the chip. Don't just do it to the chip as it's wired though - be sure you pull it up and give it 5V, or the original /CE signal, but not both.

aha2940 · Jul 6, 2014

mikejmoffitt said:
Stacking them is fine, but you don't want to switch which gets 5V or not, as that leaves the inputs there which will cause problems. Instead, you want them both powered, and use a switch to control which one's /CE line gets tied high vs gets the original signal. Pulling /CE to 5V will disable the chip. Don't just do it to the chip as it's wired though - be sure you pull it up and give it 5V, or the original /CE signal, but not both.

This is exactly what I needed to know, thanks a lot for the information mikejmoffitt, I'll search for the chips pinouts, try this and report back how it goes. Now all I need to get is the burned P roms (or an EPROM burner and EPROMs)

Thanks!!

fremen · Jul 7, 2014

Hi dudes,

it could be better if you burn an eprom and control the high lines with a switch in order to activate the first one or the second one of the eprom halfs. All in only one eprom.

Un saludo

SNKorSWM · Jul 7, 2014

Why not just use a multicart format and have a menu to choose which version to run?

xsq · Jul 7, 2014

this sounds interesting. Keep us posted!

mikejmoffitt · Jul 7, 2014

fremen said:
Hi dudes,

it could be better if you burn an eprom and control the high lines with a switch in order to activate the first one or the second one of the eprom halfs. All in only one eprom.

Un saludo

If you have an EPROM big enough to fit both versions, then this is the better solution. Be sure to never leave any address lines floating, though, always tie them high or low.

aha2940 · Jul 7, 2014

Thanks for the suggestion, but while I understand it in theory, I would need help with the actual implementation, I am not sure how do data lines work on the EPROM chips, so I would have to learn and understand that part first. Any help with this is welcome.

Thanks!!

Sent from my mobile device using Tapatalk

fremen · Jul 8, 2014

Hi dude,

You can see how to do it, it is the same concept.

http://www.neo-geo.com/forums/showthread.php?212650-Switchable-bios

Un saludo

aha2940 · Jul 8, 2014

fremen said:
Hi dude,

You can see how to do it, it is the same concept.

http://www.neo-geo.com/forums/showthread.php?212650-Switchable-bios

Un saludo

Thanks for the link, fremen. The theory seems to be what I had in mind, but this also explains the details, like the chips to use and legs that allow the switching.

This will take some time for me, because I do not currently have an EPROM burner, so I should first get one, then do my testing (planing to use my AES magician lord and MVS Korean Shock Troopers) but I will report how this goes.

GadgetUK · Jul 9, 2014

The cleanest method (depending on P1 size isn't greater than largest of that EPROM type) is to get an EPROM or OTP and program the chip to store 1 P1 ROM in lower half, and the other P1 in the upper half. Then put a switch to the top address pin and have it switch between ground, or 5v through a 4k7 resistor. I've done the same thing on the M1 ROM before.

GadgetUK · Jul 9, 2014

Btw - what's the other version of Magician Lord over standard MVS? Any noticeable differences?

Asure · Jul 9, 2014

Version differences:

http://www.neo-geo.com/forums/showt...n-Lord-cart-owner-please-read-and-answer-this

Ver 'h' has
- Extended life bar
- Intro
- Respawn point
- Possible jump glitch fixed?

It's just a single P1 swap, i can understand this would be a more desireable version

(All the gfx and stuff in the intro was unused assets in the original C roms anyways.)

You'll need a 27C800 and leave pins 1 & 2 not inserted on the board. You can then use pin 1 to switch to upper/lower part and, between the two game versions.
(Original board has a MB834200 and the pinout seems to match for me, at a quick glance.)

Solder three wires to a three-point switch like below:
- PIN goes 1 to center of the switch.
- PIN 31 goes to the left terminal of the switch.
- PIN 22 goes to the right terminal of the switch.

GadgetUK · Jul 9, 2014

Very interesting! I will definitely do this mod to my cart, to allow both versions. Got me interested in other different revisions of other games now lol. Just read something about a different revision of Shock Troopers as well.

aha2940 · Jul 9, 2014

Asure said:
Version differences:

http://www.neo-geo.com/forums/showt...n-Lord-cart-owner-please-read-and-answer-this

Ver 'h' has
- Extended life bar
- Intro
- Respawn point
- Possible jump glitch fixed?

It's just a single P1 swap, i can understand this would be a more desireable version
(All the gfx and stuff in the intro was unused assets in the original C roms anyways.)

You'll need a 27C800 and leave pins 1 & 2 not inserted on the board. You can then use pin 1 to switch to upper/lower part and, between the two game versions.
(Original board has a MB834200 and the pinout seems to match for me, at a quick glance.)

Solder three wires to a three-point switch like below:
- PIN goes 1 to center of the switch.
- PIN 31 goes to the left terminal of the switch.
- PIN 22 goes to the right terminal of the switch.

Thanks a lot for the help Asure!! this for sure helps a lot. I checked the pinout on the 27C800 (http://pdf.datasheetarchive.com/datasheetsmain/Datasheets-6/DSA-110704.pdf) and it matches the MB834200 (which is here: http://www.euro-arcade.de/files/romref.txt) from Magician lord for sure (it only adds A18, the other pin says NC, which I assume is Not Connected). So to be clear: what I should do is to create a file that is both P1 roms one after the other, the resulting file should be 1MB since the P1 rom is 512kB, and then burn that to the 27C800 right? then the switch you suggest switches between GND or +5V to the A18 pin, which I assume is the one that controls the bank presented by the cartridge, right?

I'll do this as soon as I can get the burned chip and report back how this goes. Two questions though: does it make any difference using a 512Kx16 or 1024Kx8 chip? or it's completely transparent to the Neo Geo which chip I use? also, which speed should the EPROM be? the faster the better or are there speeds that work / don't work?

Edit: I looked into the requirements for this mod on Shock Troopers, here's what I found:

- Original cart has a TC538200P chip (http://www.mvs-scans.com/images/0/0e/Shock_troopers_set2_b1_front.jpg)
- Pinout of the TC538200P is here: http://www.euro-arcade.de/files/romref.txt
- a compatible EPROM twice the size is the 27C160 (http://noel.feld.cvut.cz/hw/st/4622.pdf) This has the same pinout, with the added A19 on pin 42, which (I suppose) can be used to control the ROM read, just like with Magician Lord.

bustedstr8 · Jul 9, 2014

aha2940 said:
Thanks for the link, fremen. The theory seems to be what I had in mind, but this also explains the details, like the chips to use and legs that allow the switching.

This will take some time for me, because I do not currently have an EPROM burner, so I should first get one, then do my testing (planing to use my AES magician lord and MVS Korean Shock Troopers) but I will report how this goes.

On an AES cart you could avoid modding the cart by switching using an interal IC. It might be nice to keep the cart original so it can fit in the box.

If you wired a 4 bit counter (HCT161) clock input to reset and then the least significant bit of the counter to the high eprom address, each reset pulse would change the game.

27C800-120 or faster....The Neo will always read the chip as 512K x 16

fremen · Jul 10, 2014

Hi,

bustedstr8 said:
If you wired a 4 bit counter (HCT161) clock input to reset and then the least significant bit of the counter to the high eprom address, each reset pulse would change the game.

Does it needed a debounce circuit like when you use a 393?

Un saludo

Asure · Jul 10, 2014

Shock troopers is a nice one to do this with as well, the differences (life bar per character) are big enough to warrant it.
Another easy one would be Puzzle de Pon (switchable to /R version but needs P1 and S1)
A project which i have been thinking about, is merging Savage Reign and Kizuna into one cart.

Can the HCT161 drive more than one chip high/low?

B35 on the prog cart edge connector is reset, we tie that to CLK , Q0 to the Address line.. Hook up GND/VCC, any other requirements? (I've never used 161

)

fremen · Jul 10, 2014

fremen · Jul 10, 2014

Hi,

I've neither use a 161, but the 393 is a double counter and in combination with a 74LS139 you can drive 4 chips with 4 different combination high/low, so 16 possibilities.

This combination is modified from snesdev forum AST scheme.

Code:

74LS139

          
                           |01 \/ 16| +5V
            74HC393 #3     |02    15| NC
            74HC393 #4     |03    14| NC
            EPROM1 (/OE)   |04    13| NC
            EPROM2 (/OE)   |05    12| NC
            EPROM3 (/OE)   |06    11| NC
            EPROM4 (/OE)   |07    10| NC
            GND            |08    09| NC

Code:

74HC393

            RESET     |01\/14| +5V
            GND       |02  13| 393 PIN#1
          74LS139 #2  |03  12| 393 PIN#2
          74LS139 #3  |04  11| High eprom direction 
             NC       |05  10| Highest eprom direction
             NC       |06  09| NC
            GND       |07  08| NC

I don't know exactly where conect the 139's pin 1, but this is used for the OE activation. The NC should be conected to GND, and a debounce circuit must be done (5v----->Cap----->393 pin 2----->resistor----->ground), the delay must be 1/10 second.

Un saludo

bustedstr8 · Jul 12, 2014

Code:

74HCT161

          
                   5V    |01 \/ 16| +5V
                Reset    |02    15| 
                         |03    14| High Eprom A
                         |04    13| 
                         |05    12| 
                         |06    11| 
                  5V     |07    10| 5V
                  Gnd    |08    09| 5V

This would work for two chips also, like a Puzzle de Pon. You could split Q0 and then install a wire to wire connection by the edge of Prog board to make cart assembly easier. Then load the bottom half of a 27C2001 and 27C800 with one game and the top half of the chips with the other. Just remember to switch /OE and A16 to match the S1 slot.

I'm not sure how this would work for a MVS setup. I would think on a multi-slot the reset is pulsed every time you select a new game, so you would need to cycle through to change the game. (Hopefully someone with better knowledge can chime in)
I just checked my 1 slot and the Z80, 68K and Prog board all receive the same power on reset, so a soft reset mod would be need to be added.

@ Freeman
I've used this setup in a Genesis before without the need for a debounce circuit. I'm guessing the Genesis, as well as the AES all ready has one by the Reset button.
If you where gonna do the piggyback method the 393/139 combo looks like it would do the trick.

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