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32kb game on a 128kb cart
Posted: Thu Dec 18, 2014 6:25 pm
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After the hoshi wo sagashite repro (thanks again guys), I was thinking if it's possible to make a cart of a 32kb game into a 128kb. game (one chip). | |
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Posted: Thu Dec 18, 2014 6:40 pm |
Yes, any cart can be modded for a 32KB game. | |
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Posted: Thu Dec 18, 2014 7:20 pm |
I've tried machine gun joe on a 27c256 and put it straight on a world soccer cart, but it won't start (alex kidd starts). |
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Posted: Thu Dec 18, 2014 8:46 pm |
...and the pinouts are converted appropriately? | |
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Posted: Thu Dec 18, 2014 9:08 pm |
So different pcb different pinouts right? :P |
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Posted: Thu Dec 18, 2014 9:44 pm |
Let's assume they're all different and start from there. | |
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Posted: Thu Dec 18, 2014 10:30 pm |
So we need the pinouts of a 32kb. and a 128kb game. And then rewire I think Sorry I'm totally new to this :) |
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Posted: Thu Dec 18, 2014 10:38 pm |
That game will not boot on a stock western system because it has no header. | |
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Posted: Thu Dec 18, 2014 11:13 pm |
Yep. This. |
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Posted: Thu Dec 18, 2014 11:20 pm |
So 32kb. games dosen't have the header right? |
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Posted: Thu Dec 18, 2014 11:23 pm |
Some of the ones released only in Japan, yes. The rest do. | |
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Posted: Thu Dec 18, 2014 11:27 pm |
So if I had a japanese bios on my sms2, the game should start |
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Posted: Thu Dec 18, 2014 11:31 pm |
If the last 16 bytes aren't used, it's probably better to just add the header, rather than BIOS hacking ;) | |
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Posted: Thu Dec 18, 2014 11:40 pm |
right ;) Well last time I've learned how to change some parameters of the header. Now how to add a header? :) |
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Posted: Fri Dec 19, 2014 12:39 am |
Well, I've got some bad news... it looks like it is not as straightforward as one would like. In this case, 0x7FF0-0x7FFF isn't just blank space. So it's possible that the data in that space can be remapped, but it might involve disassembling the ROM and reassembling it with some things moved, if it's possible at all... | |
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Posted: Fri Dec 19, 2014 12:57 am |
:( by the way, to put a 32kb rom on a 128 cartdrige i need to rewire something? |
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Posted: Fri Dec 19, 2014 1:02 am |
A 128KB cart will have a mapper IC. If you remove the mapper IC and just wire the address/data/control lines of the ROM directly to the cartridge connector (preferably finding the relevant solder points, and not actually soldering to the edge connector), then it should work. | |
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Posted: Fri Dec 19, 2014 1:05 am |
I would assume the 32pin mask rom you are removing is pin compatible with a 27c010, so compare datasheets and for example put the EPROM so that 27c256 A12 (pin 2) sits where 27c010 A12 (pin 4) would sit, but that's just an example - compare datasheets/pinouts. Probably the 27C256 would sit with 2 rows of solder points empty above pin 1. Whether a 27C256 is compatible with a 27C010 is again down to pinout comparison. | |
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Posted: Fri Dec 19, 2014 2:36 pm |
Ok
This is the donor: World soccer - 28 pin rom I just look at the rom list and this is a 128kb game. |
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Posted: Fri Dec 19, 2014 3:12 pm |
You should trace the pinouts from the cartridge slot to the chip and then compare to your EPROM's pinouts. Or you can see if someone already did that:
http://little-scale.blogspot.co.uk/2008/06/how-to-make-32kb-sega-master-system.h... It seems you may be in luck, I'm sure you need to rewire things in other cases. |
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Posted: Fri Dec 19, 2014 7:41 pm |
Before going to that effort, it might be good to figure out how to get a header onto the ROM, though, or the result won't work regardless of how it's wired up (without a BIOS mod). | |
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Posted: Fri Dec 19, 2014 10:18 pm |
Indeed, I've relocated stuff for headers before, but it takes a bit of luck to find what the data is used for. On such a small game, static analysis might work wonders.
If the goal is to confirm the hardware works, just use a different ROM. |
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Posted: Sat Dec 20, 2014 1:13 pm |
In these days I will try with another rom.
Maybe satellite 7 |
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Posted: Sat Dec 20, 2014 4:30 pm |
Or maybe a tested and working 32kb. game it's better
I like a lot the three dragon (but it's super hard) :) |
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Posted: Sun Dec 21, 2014 1:02 pm |
You might be able to add a header to Satellite 7 using a hex editor.
At 0x7FF0, change the final 16 bytes to: 54 4D 52 20 53 45 47 41 4B 2F 83 5D 04 05 00 4C See if that passes the Header Reader tool's checksum check when you're done. If so, then it's probably a suitable test ROM. |
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Posted: Wed Dec 24, 2014 12:26 am |
Checksum Check passed. I will try this one :) |
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Posted: Thu Dec 25, 2014 3:48 pm |
Perfect! this works flawlessly. Thanks :)
There are others good 32k. games? |
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Posted: Thu Dec 25, 2014 3:52 pm |
P.S.
Merry christmas :) |
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Posted: Thu Dec 25, 2014 7:22 pm |
Pretty much all the 32KB games are good, basic gameplay driven games. | |
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Posted: Fri Dec 26, 2014 12:05 pm |
Awesome, glad to hear it worked. So now if someone has the time to figure out a way to remap the last 16 bytes of data in the ROM, you'll get your Machine Gun Joe.
I have fond memories of Spy vs Spy (not on SMS, but the SMS version is 32K), and My Hero (Seishun Scandal). My Hero is a goofy game but for some reason I really got into it. As long as you use the US/Euro releases, there shouldn't be a need for header hacking. |
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Posted: Fri Dec 26, 2014 2:08 pm |
I had a look at Comical Machine Gun Joe. The data at $7ff0 is for level 6 (fairyland). There is a table at $1EB9 which points at data for each stage; the 7th entry is $7fa3. The data there seems to run up to $7ff8 (the data pointers are 55 bytes apart). (This means the last 8 bytes of the header are intact - and they seem reasonable.) You'd have to relocate all 55 bytes, and as far as I can tell there is no slack space, so it'd be a larger effort of data recompression to make the necessary space. Alternatively, you could expand the ROM to 48KB. A final option is to remove the Mark III logo splash and use the space freed up. That will also take a bit of work.
Another option would be to put a header in at $1ff0 or $3ff0 - the former is some code and the latter is some data. They might require relocating fewer bytes. There's still no free space though. |
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Posted: Fri Dec 26, 2014 3:22 pm |
Yeah, looked pretty full to me at first glance too.
I wonder if there are any pirate versions of the game that have the Mark III logo removed already? EDIT: Well, removing the Mark III logo will definitely open up the necessary space (over 220 bytes are used for it). I was noticing that the USA/Euro ROMs have a lot more unused space near the end... probably how they did it in many cases. EDIT #2: I notice that you mean 0x55 bytes after re-reading this. Still plenty of space in the Mark III logo. |
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Posted: Fri Jan 02, 2015 6:28 pm |
I don't know where to start :D | |
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Posted: Fri Jan 02, 2015 6:43 pm |
I made a hacked one which probably will work, but the Mark III screen is now garbage. I meant to go back and find the call to it and just skip it, but I haven't gotten back to this. | |
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Posted: Fri Jan 02, 2015 8:49 pm |
:) |
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Posted: Thu Jan 19, 2023 8:10 pm |
Sorry to resurrect an old thread but I find this interesting.
In the tutorial for modifying a master system game at https://www.smspower.org/Development/128kEPROMModificationFor315-5208BasedSMSCar... so it works with a 27C010 1 mbit eprom with a 315-5208 mapper ic. Can I use a SST39SF010A instead of the 27c010? Though some of the pins are different I think it is possible -the WE will need to be pulled high of course. Though I's ask for an answer in case I overlooked something. SST39SF010A is the cheapest flash IC I could find to use here (the others cost more than 10USD per IC) SST39SF010A is about 2USD if bought in bulk. |
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Posted: Fri Jan 20, 2023 12:00 am |
Make sure to connect the correctly-named address line correctly, and that's all you should have to be careful about. And, yes, as you guessed, tie flash /WE high. | |
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Posted: Fri Jan 20, 2023 12:39 am |
After some more thought I realised there may be a problem, suppose we use a plastic cartridge case instead of a bare bones PCB, using the IC because it is CMOS it is more likely to fail if the edge connector on the cartridge PCB is touched due to static electricity; the question is then how likely it to be damaged from such a situation-higlhy likely? or not? If it is removed using its plastic shell then it is probably safe? |
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Posted: Fri Jan 20, 2023 12:54 am |
Modern SST39 flash is no more susceptible to static electricity than older 27C UVEPROMs - maybe a little better - but still it's a good idea to to be careful. | |
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Posted: Fri Jan 20, 2023 5:19 am |
It is required to touch the CMOS IC to pull and plug it into the DIP socket with hands. I guess adding a reverse diode across the power to the IC will add some extra protection against static electricity. 1n4001 diode is what I have in mind here. |
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Posted: Fri Jan 20, 2023 5:31 pm |
The chips themselves have some amount of static electricity protection built in - it's somewhat famous how easily you can accidentally destroy a bare MOSFET like a 2N7000.
My understanding is that the 1N4001 is too slow for ESD purposes. I haven't yet destroyed any of my Flash ROMs my accidentally touching the board or ROM, so it doesn't seem obviously useful to me. You can ask the internet for designs to add ESD resilience beyond the diodes that are already inside the ROM. My understanding is that some designs where static is a known threat add specially-shaped spark gaps on the PCB. |
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Posted: Fri Jan 20, 2023 9:57 pm |
I bought some cheap CMOS ICs (not flash memory) today and made a circuit from them and handled them to test if they would be damaged and they still worked-though they are not memory ICs I think that is evidence CMOS flash memory along with your experience above that modern memory ICs are robust-I didn't know these memeory chips had built in protection-so I am going to buy a SST39 as it will be likely okay. On the other hand I do remembers repairing an 1980s era home computer, about 5 years ago,that has CMOS memory and with one quick touch some of the memory waws damaged-of course 1980s memeory is a different generation of technology from todays's flash memory.I suspect these 1980s memory ICs did not have built in protection. |
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