Pre-Gen

News are slow lately and I’ve been told some people find old electronics interesting – so I’m going to present one of my latest “experiments”. It’s mostly to brag but but if you find it useful, all the better.

I’ve bought several 386 mobos, each cost me about 10 Euros (and a couple more for shipping) and all were described as dead, not booting. Nothing really surprising about it, pretty much all of these have old NiCd battery on them and those are notorious for spilling their guts and corroding the copper – sometimes to the point where the traces and vias are completly gone. If you ever get one of these, and the battery has not beeen removed or replaced, desolder it ASAP.

Here’s the seller’s photo, all in all the mobo looks in pretty good condition but you should be able to spot the greenish corrosion already:

The spill wasn’t that bad – water+brush, vinegar+brush, water+brush, and the PCB started looking way better. Actually there weren’t any broken connections but some solder joints and traces were corroded to the point where I decided to rework them. Better to spend 15-30 minutes now than hours later figuring out why things randomly don’t work.

If you paid attention you noticed one of the plastic support pegs was still in the board when it was sold. Turns out there is a reason for it, it’s a very tight fit and I had some serious trouble removing it. I’d just cut it off, if it wasn’t for the fact these old pegs come in handy if you want to put the mobo inside an AT case. But apparently I wasn’t the only one who tried to remove it and someone before me was not as careful with their tools. There were deep scratches on some of the traces near the hole, and I’ve decided to remove the solder mask there and tin those over to make sure there is proper electrical connection. Again, I’d do it even if the trace showed continuity, these are ISA bus signals and there has to be enough copper on each connection to allow proper currents. Otherwise the rise/fall times are going to be absymal and that’s just asking for trouble.

I mean, look how close those traces are to the hole – right on the edge. Who designed this thing?! I could fix it in 10min in the CAD by moving some of the bottom traces to the other side, and then repositioning the hole itself a bit. I think I could get 1mm clearances on both sides without actually re-routing anything. Still not a lot but at least something. Seriously, that’s a bad job.

Alas, that wasn’t all that was wrong with this motherboard. Notice that crystal in the bottom right coner? It’s not soldered in at an angle. It’s actually sheared off, stopped only by the capacitor that got a bit damaged in the process as well. That had to be replaced but it’s easy – if you have the parts. I didn’t so I’ve replaced it with 14.7456MHz and now it’s a bit overclocked mobo.

Does it work now? It does! That is, after I’ve put on some missing cache size jumpers.

That’s a seriously impressive BIOS for such a cheap mobo. Or so I thought. Well it turns out the BIOS has quite a few options that the motherboard / chipset doesn’t actually support. When I was trying to map the PGA132 socket connections I noticed that A20M# signal is indeed connected – but only to the keyboard controller. Not to the chipset. So how does a Cyrix CPU work with “Fast Gate A20” set to enabled? Maybe it doesn’t. Or maybe the “Fast Gate A20” option can’t be set at all, becasue it’s not supported, as I’ve learned few hours later.

It’s required to turn off the Turbo Switch function if you don’t have an actual switch connected – because it defaults to slow. A minor annoyance but took me 15 minuts to figure it out. I thought my test card was somehow slowing down ISA but to a crawl.

UPDATE: Forgot to mention this but the ISA clock setting of 14.3181/2 doesn’t work either. At least it’s easy to spot, the mobo will just freeze with speaker tone on, during boot. Only CLK2 dividers work and there’s not a lot of them so for 20MHz bus you will get a lousy 6.67MHz ISA clock.

You can set the Cyrix CPU to BARB or FLUSH but the FLUSH# input is not connected at all. So BARB it is. I’m still unsure if the mobo properly supports the hidden RAM refresh (forgot to check with the scope, will do it later) but at least there is a performance difference between L1 off and L1 on with BARB enabled. So it might just be working properly and not flushing the cache every 15us. But the whole purpose of this project is to experiment with the FLUSH# input anyway so it’s not a huge deal either way.

Well then, time for the mod:

The mobo does have an empty space for PGA132 socket but apparently it was supposed to have either the socket, or the PQFP CPU soldered in. Not both. So there is no jumper to disable the PQFP CPU and I had to solder a wire to FLT# input myself – though at least the empty space for the alternative clock generator and it’s two jumpers allowed me to easily add a jumper of my own. Then I’ve soldered in the socket and put in the Cyrix. And what do you know, it works well.

That was about 20 Euros in parts and a whole afternoon of work but now I can easily test PGA132 CPUs wihout having to mess with the FM Towns machines. I can do most testing and code dev on this PC. There is no 16MHz clock selection but there is (undocumented) 20MHz and it seems my 16MHz CPUs work at 20 as well. I could aways add a clock divider to the 33MHz setting but that would require more work and with high frequency signal (66MHz to be divided by 2) which is always tricky. Might not work with just wires and so I’d have to design some sort of add-on PCB to stack over the clock amp 74F gate – not that difficult but it’s more time and money spent. So I’d rather not.

54 thoughts on “Pre-Gen

  1. I use lemon juice rather than vinegar, not because it’s any more effective, I just prefer the smell!

  2. Nice to see that these old motherboards can be brought back to life and put to good use.

  3. This stuff excites me as much if not more than Sega Saturn. It’s too bad you are always so busy and stressed. We would have great conversations.

  4. One day I will build an old 386 or 486. It’s basically the first computer I ever used (with Windows 3.1). So I’d like to have one to mess around with. Problem is the parts are getting harder and harder to find.

  5. GDEMU.. Any more Doc Brown Invoices gone out?

    Any idea if Phoebe or Rhea will come up for sale soon?

  6. I just received a Refund from Clanet on Paypal for my Phoebe, was it lost in transit?

    • Quake requires 32MB of RAM and 4MB 30-pin SIMM sticks are kinda expensive for what is basically a on-the-side research project.

      • I was saying that as a joke, because Quake basically killed Cyrix processors due to the non-existent FPU.

  7. How long does it take from Poland to the US? I ask because it left Poland on the 21st and the tracking has been dead since then with USPS being unable to track it.

    • It usually takes a good 2 weeks from what I have seen in the past. I am in the Dallas area so I guess it could be longer if you are on the West coast.

    • Tracking usually does not work in the USA.. unless you call and ask over the phone, then they can usually tell you where it is, but internet 99% of the time tells you nothing

      • How do I do that? I don’t speak Polish, so I don’t know it that works for me

      • And you misunderstood….

        Tracking online does not work. CALL USPS if you need an update they can tell you where it is. POLISH NOT REQUIRED…

      • Just got off the phone with USPS. Apparently, it’s never even left Poland yet and it’s been two weeks since it shipped. It shows up on their end as Origin Post Is Preparing Shipment. Does it usually take two weeks just to leave the country?

      • Have a bit of patience. IT goes one of Two ways. AIR or BOAT.

        if it goes air it usually takes 5-6 weeks tops. I usually get mine (in the USA as well, east coast) in about 4-5 weeks if it left Poland by air. I have had a few that took 6 weeks.

        Now If it goes by boat it can take a WHILE.. I have had many different arrivals, the longest was 75 days. Some other packages from Poland that go by boat usually take about 9 weeks. So about 60 days or so. I have been ordering from D for 4 years now. I have ordered MANY MANY cards from him and some arrive ASAP (like I said 28 days or so from the day I get tracking) others have felt like they were lost in the mail. The one that took 75 days. I was convinced it was missing, lost, gone, ect….. On the advice of GDEMU i called the 800 number and asked them to see if they knew where it was. They found it and it still took over 10 days and it was in the USA already.

        Sometime USPS just takes it’s sweet ass time and then blames it on customs or overseas carriers. That is why when tracking does not work from a foreign country like Poland and USPS does not accept their Tracking into our system, for end users to check online, they can say whatever they want when you get them on the phone.

        It will arrive. I have no read a single person here claim they had theirs lost in the mail. In fact. I have PROOF (PICS) of a RHEA I ordered last year that arrived destroyed. The envelope was torn to shreds and they put the ripped envelope in a bag. The Address was still readable and it took like an extra 3 weeks for them to deliver it. The PCB was not broken as GDEMU does a good job of wrapping them in pink Anti-static bubble wrap, but the damage to the envelope was so bad that the corner of the PCB was scratched (just the masking) and the Button to cycle the games was damaged and didn’t work. I de-soldered the button and put a new tact on and it worked just fine. None of the scratches in the PCB were deep nor were they on tracers. None of the other components were damaged. It worked great and with a 3d printed tray you couldn’t see anything damaged once it was installed. Point is, even with a damaged parcel, as long as they can read the address and zipcode, it will get delivered.

        If you wait for than 90 days I would be concerned. But again, as long as you have the Polish post tracking, USPS can tell you something about the parcel if you call and ask.

        Be patient and just wait. It will arrive.

      • I called Polish Post and Magdalena told me that left Poland on the 21st and it’s being sent Priority International. She said that if it’s not here by Friday then I should worry.

      • Yes seriously. Since you don’t want to file the complaint with these people and I cannot as the receiver, I still don’t have what I paid for.

        It’s been FOUR WEEKS already since it left Poland and it STILL isn’t here.

        As for your excuse that it “goes by boat”, I’ve had now TWO reps from Poland Post tell me that what you sent was a “Priority Registered Letter” and it was sent by PLANE, not boat. Not only that, but the only things to go by boat are “Economy International Letter”. Also, they told me as I just AGAIN got off the phone with a THIRD rep(and I have to pay for these calls each time) and they informed me that it is three weeks the LATEST for such an item to be delivered to my P.O. Box. As the receiver I cannot file a complaint and have Poland Post look into it, only the SENDER can. So, being you refuse to help and file the complaint with them to find out where this item is, yes I have to file a dispute. If you were willing to help and file the complaint as I told you to and call them like I was instructed by them to have you do, then there wouldn’t be a problem.

        I have had nothing BUT patience with this whole process, but the fact that you don’t take care of issues that arise when they do happen show me that you I cannot work with you on a solution. I can only do so much as a recipient. I just want the Phoebe here. I don’t care about the money as I already plunked down money for a Saturn complete in box, an SD card, mounting tray, accessories, and the like to enjoy this. So, even if you somehow offered to send another Phoebe via a faster service, I would’ve done that. But you chose to sit here and make excuses when I’ve clearly explained to you what they told me and what you had to do as the seller.

        I buy and sell movies and the like all the time and those few times there’s a problem, I make it right. Because at the end of the day, I want people to be happy. I understand to you it’s a “hobby”, but when money’s involved, it’s not a hobby anymore.

        I’ve taken my time and see if it got better but it didn’t. It’s still the same. That’s why it took me a while to write back.

        Even now you have to admit that this isn’t normal and will hopefully and finally call these people and have them find out where this board is.

      • You always belive everything a phone rep has told you? Because I might have a cheap bridge for sale.

        My point is this – PayPal will refund you out of my pocket because it’s their policy, they don’t care about the package, the customer is always right. Well I do care about the package and so if I find (and I will) that you got both your money back and the device delivered I will file ecommerce fraud complaint with the police.

      • You go right ahead. I have half of the damn state looking for it and I wouldn’t be this angry if I actually received it. But you keep avoiding the issue and thinking you’re right all the time. Do you WORK there? Are YOU the one trying to find this thing and looking for it? No? Well then, you got nothing to be angry about. This shows what kind of person you truly are that you’re actually getting mad at ME for wanting what I paid you for. Even if I do get the money back, and you’re even dragging your feet in responding, what good is it? I still don’t have the board. I’m the one making all these calls. I’m the one trying to find it. Meanwhile, you and your people are crucifying me in a public forum. You can threaten me all you want, but YOU are the one not helping and being uncooperative. NOT ME.

      • Half the state, right. Helicopters and rescue dogs too I guess? I’m sorry to hear 130 EUR is such a big deal to you, perhaps you should not have bought such expensive toy in the first place then?

        All that being said, I’ve shipped quite a few of these to USA and I speak from experience. What do you have, other than your own idea on how fast postal services between 2 continents are and a bunch of fairy tales from reps who would cut their tounges off before admiting company’s fault.

        Your problem is you are being terribly impatient. All you have to do is wait. Not call, not search, not open disputes. just WAIT. It’s in the mail – literally.

      • WOW what a huge tool this guy is.

        Did you serious PAYPAL dispute GDEMU?? That is so wrong.
        The Guy has shipped 100’s of cards..
        Clearly some take longer than others.
        I hope he never sells you another thing ever again…

      • GDEMU…

        If you get the card back… email me.. I will gladly buy it. I can use another Phoebe.

      • For those that have contacted USPS – do you know if the automated tracking system is sufficient or does one have to talk to a representative?

        disclosure: no intention of opening a paypal dispute if the package is not as far along as I would wish – just curious 🙂

      • Tracking for any of GDEMU packages do not work online for USPS customers.

        You have to call, talk to an agent and give them the tracking over the phone.

        They might not have exact tracking if it is not in the USA yet.

        If it is in the USA or in Customs they can tell you where it is, but not how much longer it will take.

      • I think I was not clear which is my fault – I was trying to draw a distinction between the automated phone system vs waiting 2 hours to talk to a person on the phone. I tried to talk to a person today but after waiting an hour for a callback the person tried to transfer me to the international people which had me on hold for 45 mins before I gave up.

        I am assuming the automated phone system is no better than online but was hoping someone would say that I didn’t have to wait for the person and somehow their automated phone system is good enough.

      • You were clear….

        The Phone system and “TALKING” to a person does what tracking does not.

        That includes online USPS and Over the phone USPS automated (which just interfaces with the online system when you use it).

        Yes. call and place a request for international operator.
        Select option to have them call you back.
        Go about your day and the 2 hr wait will fly by.
        If you want to sit on hold for 2 hours you can do that too.

      • I am sorry but TWINIFAMI you are 100% wrong here.

        You agreed to his terms and conditions.

        https://gdemu.wordpress.com/ordering/terms-conditions/

        If you didn’t read them that is your fault.

        I am sorry but GDEMU does not scam people. EVER. He has been selling ODE cards for over 4 years now. He has Writeups from some of the biggest internet gaming personalities and with close to 7500 comments written by endusers here (which would take you about 5-7 hrs depending on your reading speed) to read through, there is maybe 2 people who have publicly posted issues with them getting there card. GDEMU will resolve your issue if there is one but you have to let the 9-12 week scenario play out. I can confirm as a US buyer that some times packages go really slow or get bounced around the system and can take what seems like forever, almost like it is lost. I was in that situation once and I was patient and it did finally arrive. Again reference my experiences above.

        4 weeks is nothing…. Nothing at all. You really shouldn’t have opened a case. First off you agreed to his terms and conditions which pretty much prohibits you from doing so, second you seem to be really edgy and impatient. You want what you want and you want it right now. That is not how this works. I am still waiting on an invoice from 2 months ago for a card I ordered. I have waited nearly 3 months for cards to arrive in the mail. I have over 25 orders with GDEMU over the 4 years he has been here and I have never had an issue ever. Even when I thought I did, he was nice about it and I didn’t go jumping to any conclusions.

        KEEP THIS IN MIND – Paypal has a 6 months policy. Opening a case after 2 weeks is ridicules, based on his reputation and length in the business of offing his ODE to the world, you should give it 9-12 weeks which is what it takes should that package have been put on the board mail route. It happens a few times a month and if your package unluckily ends up on the boat as opposed to air mail you are gonna wait and wait and wait.

        If I were GDEMU, your address, paypal, email and all just got put on a blacklist to never sell to ever again. You make other US buyers look bad.

        GDEMU – this guy is a clown. He is not worth arguing with. You know how to do your thing. You know how to use USPS phone system better than most Americans. DO your thing. We will have your back. Your ODEs are some of the best retro gaming products on the Market today. We continue to thank you for that.

      • Since I know that no sane person can read one of Abe’s dissertations I’ll add a more brief comment. I’ve been waiting since Feb. 18 for my Phoebe. I am not worried. Anyone that orders things from central or eastern Europe to NA regularly knows that although it usually takes 2-3 weeks, every once in a while it takes a really long time. Potentially 1-2 months but maybe a little more in some cases. Just relax and wait patiently, it will eventually arrive.

      • TwinFami – No one is crucifying you in a public form . You are the one who has decided to put your absurd behavior on display.

        This guy started flashing warning ‘do not do business with me’ lights as soon as he started his incessant querying about where his payment invoice was.

        Anyway, to add another anecdote on delivery times, regarding my own order – for which I received shipping confirmation on the 15th and tracking shows it left Poland on the 23rd – I have made my grand total second call to USPS today. Apparently it just arrived in NY yesterday and should hopefully be making its way to me in the midwest sometime next week.

    • I got my shipping conformation on the 20th, I live in the south east US and I just received my unit today. That’s 12 days so depending on where you are it could take about as long if you are close to this side of the country or a little longer if the package has to travel across more state lines. Hope that helps.

    • I haven’t received a phoebe payment email yet. I’d appreciate it if you could check.

  8. Now that you mention it, I’ve got a couple of Socket 3 MB’s that that I should probably get out of storage and desolder the batteries.

    I also got a compact flash IDE drive to use on these systems so I don’t have to worry about getting an old HD that works. Still need to find my old IDE interface cards, but that’s half the battle at least.

  9. Just for reference on shipping times- I live in Alaska and got a payment request on Jan 7 for the gdemu. I received the board on Feb 8, so about a month from the time I paid to the time it arrived.
    Shipping never updated, it just says shipped.
    Keep up the good work.

  10. I received my Phoebe yesterday. The post office tried to deliver it on 3/19 but I missed them so I had to pick it up yesterday.

    USPS is somehow able to see more than what is even on the Universal Postal Union tracking. The first time I called the people didn’t seem to try at all to find the package. The second time I called a few days later the person noted the package hit customs the night before (this was last week). Just my experiences.

  11. Hi gdemu, firstly I must say that Rhea has been working wonderfully on my old japanese grey Saturn for quite a long time! It has totally opened the console to me which has not been possible before. (Here in Finland Sega Saturns are quite uncommon).

    If you have any news to share about PC Engine ODE in any future posts, I could imagine many would be really enthusiastic about it. 🙂

    I just tried my CD Rom unit with IFU and yeah, it didn’t work anymore (changed the broken cog and repositioned laser pots long time ago and it worked for some time, never flawlessly). These really are dead lasers for good.

    So if PC Engine ODE will ever come to be, I would buy it in an eyeflash! Terraonion’s Super SD System 3 won’t be suitable for me. Expensive, little too much original hardware is replaced and in my situation, I have all the RGB mod, Super system card and CD units. If just the laser would work.

    But whatever the case may be, keep up the great work! I could imagine that your work has made lots of people very happy and it’s good to say it out loud. 🙂

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