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I've been trying to wrap up collecting all the Japanese exclusive games I don't have, and I recently picked up a copy of Space Slalom for the SG-1000. Space Slalom is one of the carts that's normally horrendously expensive, which is why it was one of the last ones left for me to get.

Anyway, I ended up buying a copy where the shell was horrendously damaged, since it was significantly cheaper and I figured I could just transplant the board into a new case.

Through the Google auto-translation the listing said roughly something about the game not being playable and being sold for repair, so I was keeping my fingers crossed that it was merely the damaged cart that was keeping the cart from being played.

Anyway, it arrived today and I took apart the damaged cart to put the board in a new cartridge shell, and I took pause when I got a good look at the board. Now I'm no tech expert, but I've learned quite a bit from reading on this site over the years, and this board looks to me like it has an eprom on it instead of a standard manufactured game rom. The board looks legit, it's got "copyright Sega 1983" on the side, but I'm thinking this rom might have been replaced.

Is there anyone in here that has experience taking apart SG-1000 carts and can tell me whether Sega manufactured carts like this or if I got burned?

IMG_20240320_141740.jpg (174.21 KB)

Cart Image

That UVEPROM there has a date stamp of "8337" - the 37th week of 1983. That matches the date on the PCB, so it's less likely it's a fake.

Lots of early games for a certain other console *cough cough* were manufactured using UVEPROMs - the cost of making a mask ROM is a large up-front cost, and they may not have known how many they were going to sell.

The adhesive around the window - did you remove the sticker, or did it come that way? Usually there's supposed to be a metal tape one to block blue and UV light from erasing the UVEPROM.

hoping that the EPROM contents aren't already gone, put some thick sticker on that window, and see if you've got any chance to dump the contents...

lidnariq wrote

That UVEPROM there has a date stamp of "8337" - the 37th week of 1983. That matches the date on the PCB, so it's less likely it's a fake.

Lots of early games for a certain other console *cough cough* were manufactured using UVEPROMs - the cost of making a mask ROM is a large up-front cost, and they may not have known how many they were going to sell.

The adhesive around the window - did you remove the sticker, or did it come that way? Usually there's supposed to be a metal tape one to block blue and UV light from erasing the UVEPROM.

That's how it looked when I opened up the cart. No sticker inside. So Sega would sometimes use these programmable roms instead of dedicated rom chips? Any idea whether it was only for SG-1000, or if they continued the practice into Master System and beyond?

From what I've read, eproms are only supposed to last around 10 years, and then the charge holding the data runs out, so it kinda stinks knowing that my SG-1000 carts might have a limited shelf life. Fortunately, I've tested virtually all of my SG-1000 carts and I was able to get all of them running, so far.

This is what the cart looked like when I bought it. I figured I had a fighting chance of getting it running.

3595df5.jpg (99.83 KB)

As bought

I'm assuming that when the original Japanese owner of the cart said it didn't work, it may have actually been from light getting into the cracks in the casing and damaging the stickerless uveprom, as opposed to simply the shell being damaged. I'll know for sure when I test it tonight.

With that in mind, I have a follow-up question: if that data on the uveprom IS damaged, would it be possible for me to reflash the uveprom with the rom?

lidnariq wrote

Lots of early games for a certain other console *cough cough* were manufactured using UVEPROMs - the cost of making a mask ROM is a large up-front cost, and they may not have known how many they were going to sell.

OT response but I don't first-party manufactured games did that (only games from the very few third parties granted permission did that, and the only one I specifically recall doing it was the first few IREM games, which had an LED). I thought epoxy blobs were a more preferred form of cheap manufacturing, which I know Namco did.

The King of the Mods wrote

if they continued the practice into Master System and beyond?

Sega integrated the mapper into the same package as the ROM on the vast majority of Master System releases, so it'll be limited to - at most - the games that game with separate mapper and ROM chips. I suspect it's only prototypes.

The King of the Mods wrote

From what I've read, eproms are only supposed to last around 10 years

I don't think I've ever seen a UVEPROM rated for that little time. 20 years at the minimum, later often 100 years. Unfortunately, the datasheet for the MBM2764 doesn't seem to specify a retention (in years) nor an endurance (in erase+program cycles), which feels unusual to me.

Antifuse PROMs (not what you have) are famous for failing quickly.

The King of the Mods wrote

With that in mind, I have a follow-up question: if that data on the uveprom IS damaged, would it be possible for me to reflash the uveprom with the rom?

Yes, absolutely. The electrons leak out of the floating gate over time, so you can shove some more back in. I don't know if a normal programmer will do the correct thing (i.e. skip) addresses that already have the correct contents.

KingMike wrote

OT response but I don't first-party manufactured games did that (only games from the very few third parties granted permission did that, and the only one I specifically recall doing it was the first few IREM games, which had an LED).

Yeah, very few N-manufactured games had PROMs. The only one I found in nescartdb is https://nescartdb.com/profile/view/4593/mike-tysons-punch-out

Still, a noticeable number of Famicom games in 1983-1985 were on UVEPROM, e.g. Konami https://nescartdb.com/profile/view/1778/yie-ar-kung-fu and Jaleco https://nescartdb.com/profile/view/1545/formation-z

KingMike wrote

I thought epoxy blobs were a more preferred form of cheap manufacturing, which I know Namco did.

chip-on-board is definitely cheaper, but UVEPROMs weren't about being cheap - they're about paying more per unit to pay less up-front.

I got a chance to check Space Slalom last night. I just get a blank black screen, so I think it's a safe assumption that the uveprom is corrupted. I loaded up Sega Galaga right after, and it started up just fine.

So now I gotta figure out how to program a uveprom in order to restore the game to working order. I'm assuming I'll have to desolder the chip to accomodate the uveprom programmer? This is all new to me.

Any tips for getting the sticker residue off of the uveprom chip window? I was thinking either rubbing alcohol or nail polish remover.

The King of the Mods wrote

So now I gotta figure out how to program a uveprom in order to restore the game to working order. I'm assuming I'll have to desolder the chip to accomodate the uveprom programmer? This is all new to me.

You'll need access to all the pins, except pin 26. Most of them are already separated on the card edge, but pins 1 (Vpp) and 27 (PGM) are almost certainly currently shorted to pin 28 (+5V), which will prevent programming. What's the easiest way to do this is up to you...

Quote

Any tips for getting the sticker residue off of the uveprom chip window? I was thinking either rubbing alcohol or nail polish remover.

GooGone or turpentine.

So I was looking over the circuit board for my damaged SG-1000 cart and I noticed one of the traces is broken. While I still suspect the uveprom is corrupted due to the window being exposed for so long, I'm going to attempt to patch the trace and test the cart again.

I'm really curious what the cartridge's original owner did to damage the cart so badly.

As I'm likely going to end up needing to reprogram the uveprom and I have no experience in doing so, I am absolutely all ears if anyone has any tips in regards to eprom programming, recommendations on eprom programmers, etc. If there are people here that have made their own SG-1000 or Master System carts, I'm open to any advice you have for me.

20240326_033359.jpg (2.96 MB)

Broken Trace

20240326_033417.jpg (3.67 MB)

Cart Damage

From the edges of the broken plastic, it looks like the previous owner tried to pry open the cartridge before realising there are two screws hidden underneath the label.

The broken trace is D7. The cartridge definitely will not work without D7 connected. I would repair that trace, clean the edge connector, and see if the cartridge works just after that.

The EPROM is probably fine. EPROMs need a lot of UV light to be erased. Even with the sticker peeled off, the EPROM was inside a case, inside a box/draw/cupboard, away from direct (UV) light. I think it will be fine.

Should you need to re-program it, EPROMs can be programmed with the same image without being erased. Most programming algorithms work by writing a byte, reading back the byte, and doing it again and again in a loop until the byte read back is the intended value before moving onto the next byte to be programmed.

asynchronous wrote

The broken trace is D7. The cartridge definitely will not work without D7 connected. I would repair that trace, clean the edge connector, and see if the cartridge works just after that.

The EPROM is probably fine. EPROMs need a lot of UV light to be erased. Even with the sticker peeled off, the EPROM was inside a case, inside a box/draw/cupboard, away from direct (UV) light. I think it will be fine.

That's good to know. I will try to bust out my soldering iron tonight when I get home from work.

Well, I just finished soldering and then testing, and to my amazement, Space Slalom does indeed work.

So now that the circuit board is fixed I just gotta wait for my Champion Soccer cart I bought for $1.51 to show up from Japan so I can replace the shell with one that's authentic. The label sticker is too far gone, so I'm going to have to repro that, but that's fine. I'm just stoked to have a working copy of Space Slalom that's real hardware, and for considerably less than the $200 to $300 a loose Space Slalom cart generally goes for on Yahoo Japan.

To my pleasant surprise, Space Slalom is one of the games that actually looks fairly decent on the Master System (like Pitfall 2) since some of the games look pretty terrible due to the different VDP. By contrast, Sega Galaga is so dark that I'm virtually playing blind (which somehow seems to improve my game).

I ended up just using a piece of black electrical tape to cover up the uveprom window. That's fine, right?

Electrical tape is a great blocker of UV, yes. I’m curious if maybe the EPROM data is corrupted in a non-fatal way, are you able to dump it?

Maxim wrote

Electrical tape is a great blocker of UV, yes. I’m curious if maybe the EPROM data is corrupted in a non-fatal way, are you able to dump it?

I hadn't really considered dumping it, since I don't have a dumper and I was able to easily download a working Space Slalom .sg rom for my flashcart and Analogue Pocket. I assumed the rom that's already out there was fine, and likely the same.

I played it a little bit on my Japanese Master System and it seemed fine.

I gotta say I was pretty nervous doing the soldering. It was only my second time using the fine tip and soldering something that small, and I've never been particularly gifted in soldering to begin with.

Author	Message
The King of the Mods Joined: 24 Aug 2014 Posts: 53	Question about an SG-1000 cart I bought. Posted: Wed Mar 20, 2024 9:36 pm
The King of the Mods Joined: 24 Aug 2014 Posts: 53	I've been trying to wrap up collecting all the Japanese exclusive games I don't have, and I recently picked up a copy of Space Slalom for the SG-1000. Space Slalom is one of the carts that's normally horrendously expensive, which is why it was one of the last ones left for me to get. Anyway, I ended up buying a copy where the shell was horrendously damaged, since it was significantly cheaper and I figured I could just transplant the board into a new case. Through the Google auto-translation the listing said roughly something about the game not being playable and being sold for repair, so I was keeping my fingers crossed that it was merely the damaged cart that was keeping the cart from being played. Anyway, it arrived today and I took apart the damaged cart to put the board in a new cartridge shell, and I took pause when I got a good look at the board. Now I'm no tech expert, but I've learned quite a bit from reading on this site over the years, and this board looks to me like it has an eprom on it instead of a standard manufactured game rom. The board looks legit, it's got "copyright Sega 1983" on the side, but I'm thinking this rom might have been replaced. Is there anyone in here that has experience taking apart SG-1000 carts and can tell me whether Sega manufactured carts like this or if I got burned? IMG_20240320_141740.jpg (174.21 KB) Cart Image

lidnariq Joined: 24 Mar 2021 Posts: 120	Posted: Thu Mar 21, 2024 8:22 am
lidnariq Joined: 24 Mar 2021 Posts: 120	That UVEPROM there has a date stamp of "8337" - the 37th week of 1983. That matches the date on the PCB, so it's less likely it's a fake. Lots of early games for a certain other console cough cough were manufactured using UVEPROMs - the cost of making a mask ROM is a large up-front cost, and they may not have known how many they were going to sell. The adhesive around the window - did you remove the sticker, or did it come that way? Usually there's supposed to be a metal tape one to block blue and UV light from erasing the UVEPROM.

sverx Joined: 05 Sep 2013 Posts: 3828 Location: Stockholm, Sweden	Posted: Thu Mar 21, 2024 8:42 am
	hoping that the EPROM contents aren't already gone, put some thick sticker on that window, and see if you've got any chance to dump the contents...

The King of the Mods Joined: 24 Aug 2014 Posts: 53	Posted: Thu Mar 21, 2024 9:02 am
The King of the Mods Joined: 24 Aug 2014 Posts: 53	lidnariq wrote That UVEPROM there has a date stamp of "8337" - the 37th week of 1983. That matches the date on the PCB, so it's less likely it's a fake. Lots of early games for a certain other console cough cough were manufactured using UVEPROMs - the cost of making a mask ROM is a large up-front cost, and they may not have known how many they were going to sell. The adhesive around the window - did you remove the sticker, or did it come that way? Usually there's supposed to be a metal tape one to block blue and UV light from erasing the UVEPROM. That's how it looked when I opened up the cart. No sticker inside. So Sega would sometimes use these programmable roms instead of dedicated rom chips? Any idea whether it was only for SG-1000, or if they continued the practice into Master System and beyond? From what I've read, eproms are only supposed to last around 10 years, and then the charge holding the data runs out, so it kinda stinks knowing that my SG-1000 carts might have a limited shelf life. Fortunately, I've tested virtually all of my SG-1000 carts and I was able to get all of them running, so far.

The King of the Mods Joined: 24 Aug 2014 Posts: 53	Posted: Thu Mar 21, 2024 9:15 am
The King of the Mods Joined: 24 Aug 2014 Posts: 53	This is what the cart looked like when I bought it. I figured I had a fighting chance of getting it running. 3595df5.jpg (99.83 KB) As bought

The King of the Mods Joined: 24 Aug 2014 Posts: 53	Posted: Thu Mar 21, 2024 9:29 pm
The King of the Mods Joined: 24 Aug 2014 Posts: 53	I'm assuming that when the original Japanese owner of the cart said it didn't work, it may have actually been from light getting into the cracks in the casing and damaging the stickerless uveprom, as opposed to simply the shell being damaged. I'll know for sure when I test it tonight. With that in mind, I have a follow-up question: if that data on the uveprom IS damaged, would it be possible for me to reflash the uveprom with the rom?

KingMike Joined: 14 Oct 2008 Posts: 513	Posted: Fri Mar 22, 2024 3:00 am
KingMike Joined: 14 Oct 2008 Posts: 513	lidnariq wrote Lots of early games for a certain other console cough cough were manufactured using UVEPROMs - the cost of making a mask ROM is a large up-front cost, and they may not have known how many they were going to sell. OT response but I don't first-party manufactured games did that (only games from the very few third parties granted permission did that, and the only one I specifically recall doing it was the first few IREM games, which had an LED). I thought epoxy blobs were a more preferred form of cheap manufacturing, which I know Namco did.

lidnariq Joined: 24 Mar 2021 Posts: 120	Posted: Fri Mar 22, 2024 8:38 am
lidnariq Joined: 24 Mar 2021 Posts: 120	The King of the Mods wrote if they continued the practice into Master System and beyond? Sega integrated the mapper into the same package as the ROM on the vast majority of Master System releases, so it'll be limited to - at most - the games that game with separate mapper and ROM chips. I suspect it's only prototypes. The King of the Mods wrote From what I've read, eproms are only supposed to last around 10 years I don't think I've ever seen a UVEPROM rated for that little time. 20 years at the minimum, later often 100 years. Unfortunately, the datasheet for the MBM2764 doesn't seem to specify a retention (in years) nor an endurance (in erase+program cycles), which feels unusual to me. Antifuse PROMs (not what you have) are famous for failing quickly. The King of the Mods wrote With that in mind, I have a follow-up question: if that data on the uveprom IS damaged, would it be possible for me to reflash the uveprom with the rom? Yes, absolutely. The electrons leak out of the floating gate over time, so you can shove some more back in. I don't know if a normal programmer will do the correct thing (i.e. skip) addresses that already have the correct contents. KingMike wrote OT response but I don't first-party manufactured games did that (only games from the very few third parties granted permission did that, and the only one I specifically recall doing it was the first few IREM games, which had an LED). Yeah, very few N-manufactured games had PROMs. The only one I found in nescartdb is https://nescartdb.com/profile/view/4593/mike-tysons-punch-out Still, a noticeable number of Famicom games in 1983-1985 were on UVEPROM, e.g. Konami https://nescartdb.com/profile/view/1778/yie-ar-kung-fu and Jaleco https://nescartdb.com/profile/view/1545/formation-z KingMike wrote I thought epoxy blobs were a more preferred form of cheap manufacturing, which I know Namco did. chip-on-board is definitely cheaper, but UVEPROMs weren't about being cheap - they're about paying more per unit to pay less up-front.

The King of the Mods Joined: 24 Aug 2014 Posts: 53	Posted: Sat Mar 23, 2024 6:03 am
The King of the Mods Joined: 24 Aug 2014 Posts: 53	I got a chance to check Space Slalom last night. I just get a blank black screen, so I think it's a safe assumption that the uveprom is corrupted. I loaded up Sega Galaga right after, and it started up just fine. So now I gotta figure out how to program a uveprom in order to restore the game to working order. I'm assuming I'll have to desolder the chip to accomodate the uveprom programmer? This is all new to me. Any tips for getting the sticker residue off of the uveprom chip window? I was thinking either rubbing alcohol or nail polish remover.

lidnariq Joined: 24 Mar 2021 Posts: 120	Posted: Sat Mar 23, 2024 9:43 am
lidnariq Joined: 24 Mar 2021 Posts: 120	The King of the Mods wrote So now I gotta figure out how to program a uveprom in order to restore the game to working order. I'm assuming I'll have to desolder the chip to accomodate the uveprom programmer? This is all new to me. You'll need access to all the pins, except pin 26. Most of them are already separated on the card edge, but pins 1 (Vpp) and 27 (PGM) are almost certainly currently shorted to pin 28 (+5V), which will prevent programming. What's the easiest way to do this is up to you... Quote Any tips for getting the sticker residue off of the uveprom chip window? I was thinking either rubbing alcohol or nail polish remover. GooGone or turpentine.

The King of the Mods Joined: 24 Aug 2014 Posts: 53	Posted: Tue Mar 26, 2024 10:56 am
The King of the Mods Joined: 24 Aug 2014 Posts: 53	So I was looking over the circuit board for my damaged SG-1000 cart and I noticed one of the traces is broken. While I still suspect the uveprom is corrupted due to the window being exposed for so long, I'm going to attempt to patch the trace and test the cart again. I'm really curious what the cartridge's original owner did to damage the cart so badly. As I'm likely going to end up needing to reprogram the uveprom and I have no experience in doing so, I am absolutely all ears if anyone has any tips in regards to eprom programming, recommendations on eprom programmers, etc. If there are people here that have made their own SG-1000 or Master System carts, I'm open to any advice you have for me. 20240326_033359.jpg (2.96 MB) Broken Trace 20240326_033417.jpg (3.67 MB) Cart Damage

asynchronous Joined: 14 Aug 2000 Posts: 742 Location: Adelaide, Australia	Question about an SG-1000 cart I bought. Posted: Tue Mar 26, 2024 12:27 pm
	From the edges of the broken plastic, it looks like the previous owner tried to pry open the cartridge before realising there are two screws hidden underneath the label. The broken trace is D7. The cartridge definitely will not work without D7 connected. I would repair that trace, clean the edge connector, and see if the cartridge works just after that. The EPROM is probably fine. EPROMs need a lot of UV light to be erased. Even with the sticker peeled off, the EPROM was inside a case, inside a box/draw/cupboard, away from direct (UV) light. I think it will be fine. Should you need to re-program it, EPROMs can be programmed with the same image without being erased. Most programming algorithms work by writing a byte, reading back the byte, and doing it again and again in a loop until the byte read back is the intended value before moving onto the next byte to be programmed.

The King of the Mods Joined: 24 Aug 2014 Posts: 53	Posted: Tue Mar 26, 2024 1:03 pm
The King of the Mods Joined: 24 Aug 2014 Posts: 53	asynchronous wrote The broken trace is D7. The cartridge definitely will not work without D7 connected. I would repair that trace, clean the edge connector, and see if the cartridge works just after that. The EPROM is probably fine. EPROMs need a lot of UV light to be erased. Even with the sticker peeled off, the EPROM was inside a case, inside a box/draw/cupboard, away from direct (UV) light. I think it will be fine. That's good to know. I will try to bust out my soldering iron tonight when I get home from work.

The King of the Mods Joined: 24 Aug 2014 Posts: 53	Posted: Thu Mar 28, 2024 9:18 am
The King of the Mods Joined: 24 Aug 2014 Posts: 53	Well, I just finished soldering and then testing, and to my amazement, Space Slalom does indeed work. So now that the circuit board is fixed I just gotta wait for my Champion Soccer cart I bought for $1.51 to show up from Japan so I can replace the shell with one that's authentic. The label sticker is too far gone, so I'm going to have to repro that, but that's fine. I'm just stoked to have a working copy of Space Slalom that's real hardware, and for considerably less than the $200 to $300 a loose Space Slalom cart generally goes for on Yahoo Japan. To my pleasant surprise, Space Slalom is one of the games that actually looks fairly decent on the Master System (like Pitfall 2) since some of the games look pretty terrible due to the different VDP. By contrast, Sega Galaga is so dark that I'm virtually playing blind (which somehow seems to improve my game). I ended up just using a piece of black electrical tape to cover up the uveprom window. That's fine, right?

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Posted: Thu Mar 28, 2024 9:34 am
	Electrical tape is a great blocker of UV, yes. I’m curious if maybe the EPROM data is corrupted in a non-fatal way, are you able to dump it?

The King of the Mods Joined: 24 Aug 2014 Posts: 53	Posted: Thu Mar 28, 2024 10:44 am
The King of the Mods Joined: 24 Aug 2014 Posts: 53	Maxim wrote Electrical tape is a great blocker of UV, yes. I’m curious if maybe the EPROM data is corrupted in a non-fatal way, are you able to dump it? I hadn't really considered dumping it, since I don't have a dumper and I was able to easily download a working Space Slalom .sg rom for my flashcart and Analogue Pocket. I assumed the rom that's already out there was fine, and likely the same. I played it a little bit on my Japanese Master System and it seemed fine. I gotta say I was pretty nervous doing the soldering. It was only my second time using the fine tip and soldering something that small, and I've never been particularly gifted in soldering to begin with.

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