Sega CDX EEPROM part number discovered

Discussion in 'Sega Discussion' started by segasonicfan, Feb 16, 2019.

  1. segasonicfan

    segasonicfan Robust Member

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    I made a pretty cool discovery inside a CDX recently...the original EEPROM chip!
    See here for the full story.
     

    Attached Files:

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  2. Nully

    Nully Dauntless Member

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    How does Sega-CDX BIOS V2.21.bin exist if this is a new discovery? Honest question. I was curious as to why the CDX didn't have a port of the region-free BIOS when I finally picked one up a couple weeks ago.
     
  3. Bad_Ad84

    Bad_Ad84 The Tick

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    CDX does have a region free bios...

    Also ,the chip and its footprint has been known for ages. There is no drop in replacement that seem sourceable - I looked for quite some time. The MX27C1024 also comes in a SOP footprint and should match - but again, doesnt seem sourceable. You can see the drawing for the package in its datasheet.

    I dumped one with this smaller footprint from another megacd variation (wondermega? awia? i dunno, cant remember - i think it was posted on here years ago). I had a lot of work to get an adapter to fit the footprint then too. Its just not a commonly used size of chip.

    Anyway, everyone already knew the pinout matched the *1024 devices, so you just look for one of those in SOP package = chip you want. Like I said, its been known for ages.
     
    Last edited: Feb 16, 2019
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  4. segasonicfan

    segasonicfan Robust Member

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    This hasn't been documented on the Tech wiki, I was unable to come up with the part number when I searched for it, and I found no pictures of this chip with the part number like it is in this revision.

    I'm pretty sure somebody will find the post helpful.
     
    Last edited: Feb 16, 2019
  5. Nully

    Nully Dauntless Member

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    Do you have a link to a tutorial or do you sell a kit or what because I can't find anything on Google aside from a website offering the modification service. Is it just the same DIP as the model 1/2 wired to where that SMD BIOS is or what? Thanks.
     
  6. segasonicfan

    segasonicfan Robust Member

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    Yep, it looks pretty weak. I haven't done the install myself, I've only opened up and repaired one that had a previous install. I've seen pictures of them and posts on the web over the years and it it just looks heinous. I've always wanted an actual drop-in replacement that looks legit.

    Thanks to the post I just made, hopefully people will be able to do the install more easily now that they have a datasheet and pinout of the original BIOS rom that is easily accessible and stored long-term.

    If anyone sources a good 1024 SOP eeprom for this, please feel free to share with the rest of us.
     
  7. Bad_Ad84

    Bad_Ad84 The Tick

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    You don't need an exact part number. The pinout is well known to match the *1024 chips as people have been modding them with the RF bios for years. This part number you have "found" also isn't the same part number of the maskrom in other consoles. Its just the one out of a long list they could have used, they were probably the cheapest at the time.

    I also dumped the non labelled version years ago and to do that that.... You need to know what type of chip it is to read it. It was common knowledge what the pinout and type of chip was, you seem hung up on a particular part number being important, which it isn't.

    The fact they have used a generic part on some odd machines will just be supply issues of the maskroms, again pretty common occurance - you can find generic eproms with part numbers in early Saturn's too. It doesn't mean that's the part number of the maskrom, it's just any compatible chip with the correct pinout.

    It will take any *1024 chip in sop format. Same as people have been using an *1024 chip in dip with wires. It only has that Toshiba part as that's what they could get their hands on. It could equally be any other *1024 chip or maskrom, it doesn't matter.

    Literally Google any *1024 datasheet will give you the same info.

    Mx27c1024
    M27c1024
    At27c1024

    Just off the top of my head. Because they are pin compatible, they are read the exact same way,just made by different companies.


    Oh and I have a tidy replacement solution coming.
     
    Last edited: Feb 17, 2019
  8. Nully

    Nully Dauntless Member

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    Sounds good, can't wait to see it! :cool:
     
  9. abveost

    abveost Robust Member

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    The drop in replacement for that part is exactly the same as any drop in replacement for any other part they used. If they were readily available people would be using them instead of a rats nest of wires. Or maybe not. They could just put a TSOP on an adapter, so maybe they just have a wire fetish.
     
  10. segasonicfan

    segasonicfan Robust Member

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    do you know a compatible TSOP? Ill design the adapter...

    Here is the rats nest in question. This is what Im trying to do away with (attached). I had the dubious honor of repairing this beast once. (customer was very nice though, which always makes things worthwhile).
     

    Attached Files:

  11. Bad_Ad84

    Bad_Ad84 The Tick

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    This is extreme basics and something you should know if designing stuff like this.

    You can use basically any parallel eprom/eeprom/flash. The way they are read is all identical and pinout doesn't matter as you are making an adapter and can adapt it to suit.
     
    Last edited: Feb 23, 2019
  12. segasonicfan

    segasonicfan Robust Member

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    Bad_ad84 why is your attitude always so negative? You come into every thread that I start to spread negativity. I'd appreciate it if you would stop.

    None of this is extremely basic. It may be basic for you, but people have different levels of experience in different areas of electronics. I've never worked with programming eeproms before, so some of this is still new to me.

    I created this thread to help people in a positive way. If you want to contribute that's great. I just ask that you show a little more respect and a little less judgmentalness. We all have something to learn from each other here.
     
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  13. Bad_Ad84

    Bad_Ad84 The Tick

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    If you are designing pcbs, this should be basic.

    It's like running before you can walk. If you are skipping all the theory and just jump into designing stuff based on the datasheets with no understanding - you will get pulled up by people who do understand.

    I make no attempt to hide I don't like people designing and selling (or even writing guides) about things they don't understand. This has been an issue for years but is only getting worse as thing like pcb manufacturing is getting easy/cheap. People like to sell things that "work for them" but ignore sound electrical design practices.

    At best is results in people following bad mods and coming to forums like this for support and people like me and others spend time helping.

    Or at worse, consoles that aren't made anymore get destroyed - something I don't like either.

    The fact this topic exists shows you don't understand eproms or how they work. But now you are going to design an adapter.

    Like I said, running before you can walk.

    I feel like I'm turning in calpis and can totally relate to what he's been saying for years.

    Also, I don't target you or your threads. It's just that your threads are the ones that promote bad design or post stuff that shows a lack of understanding. So I end up replying to them. My style may seem critical, but I do tend to post informative information that should help you improve.
     
    Last edited: Feb 23, 2019
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  14. Nully

    Nully Dauntless Member

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    Absolutely grotesque :eek:

    I wanted to chime in that "modding" in general is just a hack-job. I take really shitty pictures that make things look way worse than they are and when I try to make tutorials I know these things are being done regardless and this way they can at least see the bare minimum of how to accomplish that goal without burning your house down. I have seen some really terrible guides online (especially Youtube videos with thousands and thousands of views) so I wanted to have something that is at most acceptable to be followed.

    I have no electronic engineering background, but I do read and listen to what anyone more intelligent than me in that field has to say as I've posted before, this is mainly just fun for me. I can do plenty of other things to make many, many times the amount of money I make off "modding" for the same effort, but my reasoning as to why I still do it is that I think the retro market is absolute bullshit and emulation isn't satisfactory, so if I can give someone the ability to play an entire library on CD-Rs for a $20-40 fee (labor) then I don't feel any guilt about not being the best of the best in this game.

    I have used the same accounts, emails, phone numbers that the literal hundreds of customers that have bought off me in the last decade and legitimately never had one tell me it didn't work right/stopped working. I've even ran into people randomly that realized who I was and that 8+ years later, their console is still working great and being played weekly.

    Wasn't sure if that guide critic was pointed at me, but yeah I mean this stuff is getting done whether you or I like it or not, may as well attempt to give some bits of useful information. Mainly I looked at some other resources and sites like mmmonkey where he's using flush cutters and lifting leads while heating pads and a bunch of other crap that's really dangerous for someone with a $5 Walmart iron and no skill to be doing. What I'm trying to do here lately is making it to where you need to invest in the proper tools before you're even able to attempt it or it's useless. The amount of failed mods I've fixed over the years is insane, the horrors I've seen on these poor consoles. :)

    I think it's great when you correct people (even me), because you are one of the ones here with true knowledge and it should be respected and they will learn that it was sound advice after the strike to their ego blows over, even if there is second-hand embarrassment. ;)

    Here's an Atari 2600 Jr. I picked up the other day as a failed AV mod for example, we have to find a way to stop this:

    [​IMG]

    His "trace repair"

    [​IMG]
     
    Last edited: Feb 23, 2019
  15. Bad_Ad84

    Bad_Ad84 The Tick

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    No, guide thing wasn't directed at anyone. Your guides you have posted have been fine and accurate.

    It's a long list of things over the years. First good one off the top of my head is the 3.3v dreamcast bios chip in a 5v va0. Then people telling me they are right as that'd what the guide says.

    There's a long long list of others. Poorly designed transistor amps for the pce, that when you plug into a TV while console is on blows the fuses is another.

    Out of spec rgb mods with wrong amplitude signals is another

    The list is almost endless. I was very much not talking about how to install a xeno or a phantom etc though. Those things have established ways to install them and some decent pictures in a guide form is good.
     
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  16. segasonicfan

    segasonicfan Robust Member

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    oh Nully was that your Multi Mega I repaired years ago?
    I really wasn't meaning to criticize you or even the person ( whoever they are ) that modded that unit. Sorry if it came out that way. I was just pointing out that a better solution is needed instead of using all those wires ( they are the correct wires by the way, 30awg and the mod does look solid ).

    I agree with your philosophy on modding. At the end of the day what's important is that the customers are happy after we add cool new features :)
     
  17. Nully

    Nully Dauntless Member

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    No, that's not mine; I was responding to Ad. But now I see what he meant. I was otherwise essentially explaining why he seemed like he was being hostile I suppose. I'm one to stay in the shadows so my insecurities about my information given lately made me think he was taking a stab at me I guess as it's something new I've been trying to do to help others, but also not wanting to be the blind leading the blind.
     
  18. segasonicfan

    segasonicfan Robust Member

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    oic I got confused since you quoted my post about the rats nest.

    Be confident in yourself and your abilities, you do good work!
     
  19. segasonicfan

    segasonicfan Robust Member

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    Luke Sanders at Console5 has now updated his site with the eeprom part number and a lot of other new information for the Sega CDX that I helped contribute towards. yay!

    I'm also considering adding a special page to my website just for the Sega CDX work that I've been doing over the years
     

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