Newbie questions...PPU / eeproms / power supplies / etc

[gable74]

Hello,
I am in the process of gathering all my pieces for my nintendo build.  I have built a few multi game jammas but I want this one to be a VS dual system cabinet which is new to me.  I know there are some differences with the VS system games and i think I am up to speed on a lot of it.  I have read and watched all of Johns tech articles and videos which have helped immensely.  This is my current setup..

1 VS system mother board populated with SMB and Excitebike eeproms and PPUs
2 nintendo color inverter/amp boards
2 19" vision pro CGA LCD monitors
2 edge connectors and wire for the harness
1 mame joystick / button kit

I am going to build the VS harness from scratch and wire everything in as usual.

A few questions that I need assistance with...

1. What power supply should I use?  It needs to be a switching power supply that provides a -5v correct?
2. Where is a good resource to purchase eeproms and PPUs in case I want to change games in the future?
3. I have an eeprom burner and eraser.  Are MAME roms the exact copy of the original arcade games assuming I choose to download and burn the eeproms myself?
4. Is there a way to burn the PPUs?

If you have any other info I may not be considering as I build this first VS game please let me know.

Thanks,
Jimmie

[John's Arcade]

ANSWERS BELOW!

1. What power supply should I use?  It needs to be a switching power supply that provides a -5v correct?

Here is the pinout:

http://www.arcade-museum.com/pinouts-game/8895.html

You need +5 and +12. The +24 shown is for the coin counter. Not needed. You do not need -5. I would personally find a working original power supply. But, since you are making the harness, you can use any old arcade type switching power supply.

This is a good middle of the road power supply:
http://na.suzohapp.com/all_catalogs/power_supplies/80-0064-00

2. Where is a good resource to purchase eeproms and PPUs in case I want to change games in the future?

I buy both of these on ebay. 2764 eeproms are easy to find on ebay for cheap. You will need to hunt for the PPUs and buy the kits on ebay with the PPU you want.

3. I have an eeprom burner and eraser.  Are MAME roms the exact copy of the original arcade games assuming I choose to download and burn the eeproms myself?

Yes, I use MAME roms. They are dumps from the arcade eeproms. Same thing.

4. Is there a way to burn the PPUs?

NEGATIVE.

[gable74]

ANSWERS BELOW!

1. What power supply should I use?  It needs to be a switching power supply that provides a -5v correct?

Here is the pinout:

http://www.arcade-museum.com/pinouts-game/8895.html

You need +5 and +12. The +24 shown is for the coin counter. Not needed. You do not need -5. I would personally find a working original power supply. But, since you are making the harness, you can use any old arcade type switching power supply.

This is a good middle of the road power supply:
http://na.suzohapp.com/all_catalogs/power_supplies/80-0064-00

2. Where is a good resource to purchase eeproms and PPUs in case I want to change games in the future?

I buy both of these on ebay. 2764 eeproms are easy to find on ebay for cheap. You will need to hunt for the PPUs and buy the kits on ebay with the PPU you want.

3. I have an eeprom burner and eraser.  Are MAME roms the exact copy of the original arcade games assuming I choose to download and burn the eeproms myself?

Yes, I use MAME roms. They are dumps from the arcade eeproms. Same thing.

4. Is there a way to burn the PPUs?

NEGATIVE.

You say 2764 eeproms?  Is that an intel chip?  Would you know where I can get a data sheet or at minimum the opcodes associated with the chip?

Thanks,

[John's Arcade]

ANSWERS BELOW!

1. What power supply should I use?  It needs to be a switching power supply that provides a -5v correct?

Here is the pinout:

http://www.arcade-museum.com/pinouts-game/8895.html

You need +5 and +12. The +24 shown is for the coin counter. Not needed. You do not need -5. I would personally find a working original power supply. But, since you are making the harness, you can use any old arcade type switching power supply.

This is a good middle of the road power supply:
http://na.suzohapp.com/all_catalogs/power_supplies/80-0064-00

2. Where is a good resource to purchase eeproms and PPUs in case I want to change games in the future?

I buy both of these on ebay. 2764 eeproms are easy to find on ebay for cheap. You will need to hunt for the PPUs and buy the kits on ebay with the PPU you want.

3. I have an eeprom burner and eraser.  Are MAME roms the exact copy of the original arcade games assuming I choose to download and burn the eeproms myself?

Yes, I use MAME roms. They are dumps from the arcade eeproms. Same thing.

4. Is there a way to burn the PPUs?

NEGATIVE.

You say 2764 eeproms?  Is that an intel chip?  Would you know where I can get a data sheet or at minimum the opcodes associated with the chip?

Thanks,

2764 is made by many different companies, Intel included.

I don't have a datasheet. I just buy them on eBay.

http://www.ebay.com/itm/10pcs-ST-2764-UV-EPROM-M2764A-64-Kilobit-DIP28-/250827525459?pt=LH_DefaultDomain_0&hash=item3a667c4d53

[gable74]

Understood.

I was actually doing some reading and saw where several authors have revised code withing the ROM data to allow certain games to save high scores.  Being Im an old techie from way back, and have dabbled in plenty of coding for chipsets, I wanted to have a look at the code on the eeprom.  Using a generic eeprom editor I was able to open and look at the data on chip 1D (the chip that holds the info for save game stuff) and make a simple compare of an altered chip vs a stock chip.  I can see where the date was changed to allow the "save game" info, unfortunately without the opcode list or instruction set, I can not decypher the code.

A snipit of code that looks like this

Code:

$000060,06 20 AD 07 20 A0 74 AD 07 20 99 00 66 C8 D0 F7
$000070,A9 02 8D 16 40 A0 05 B9 BA 66 99 D7 07 88 10 F7
$000080,20 74 92 AD 78 07 09 80 20 A5 91 4C 8B 80 01 A5

could easily be interpreted with the correct opcode set.

06 20 AD could mean branch to address 20AD or it could mean a hundred different things. 

LOL...long story short, I was just trying to find an instruction set for that particular Eeprom so I could poke a round a little.

Thanks,

[gable74]

Found my answers....

http://www.paladingrp.com/brianb/rom_hacks/ikari.html

[iankellogg]

If you want to get into rom hacking, it is pretty easy to decompile the code back to assembly.

[gable74]

Im all ears.....LOL.  You got a tool to break it down?

Good Opcode breakdown here....

http://www.thealmightyguru.com/Games/Hacking/Wiki/index.php?title=6502_Opcodes

[iankellogg]

just grab any 6502 disassembler. there are tons of them around. You can muck around and recompile if you wish or just figure out what you need to do at the opcode level and do it directly in the rom file. its really easy to set up mame to run the modified code.