No Good, contd.

It seems I have a bit of emergency on my hands. A bunch of devices shipped on June 4th got somehow damaged in transit – crushed by the looks of it. If your device was shipped on that day, inspect it well before connecting to the console. Email me if you spot any damage – I will repair or replace all affected units.

To add insult to injury – judging by the photos I got not even cardboard boxes would’ve prevented this damage. The bubble wrap needs only to last that one trip and I even got envelopes returned to me from USA being almost flat by then and yet there was no damage to the PCB or FFC. I sure hope this was a one-time event and won’t happen anymore.

But that’s just part one of the problem. Part two is I’ve run out of the plastic pegs for Phoebe because my supplier messed up, and now I’ll have to wait 4-6 more weeks to get what I ordered. This particular size is rather uncommon and hard to get. Point here is I need to keep more Type-3 ODEs on hand as replacements for the damaged ones, and with the peg shortage it means I have to pause all remaining orders. Sorry but if you are still waiting for the payment request, good chances are you are going to wait some more. Unless I can get something else to fit in there.

Peg shortage also affects Rhea – so I won’t be taking orders until this is resolved – but GDEMU is unaffected and will start shipping next week.

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No Good

Small status update: EU elections got in the way a bit more than I expected so there will be some 2-week delay shipping Phoebes. Sorry. In the meantime though I will open orders for GDEMU – that will be this Saturday around noon. Can’t say exactly when because I already know I will be busy so I might not be able to open at the precise hour.

I would like to remind you that “Is it ready yet” questions are ignored. If you can’t deal with a week or two of delay then do yourself a favour and cancel the order. You’ll be much happier. I most certainly will be.

Lastly, there’s been a plague of wrong or incomplete shipping addresses lately. It’s been so bad that I can spot these before I even ship, but who am I to question the customer. And then the package gets returned to me (sometimes I have to pay extra to claim it), the customer is angry, and I still have to re-test and re-pack the device which not only costs me money but also precious time.

So, new rule: From now on, if your address was invalid and it was your fault, I will refund you when I get the device back and your order will be cancelled. You’ll also end up on a list and I will only accept your future orders if there are devices to spare. Which is probably not anytime soon. Same goes for the name you gave on the order form and the PayPal email. If I can’t easily tell who it was that paid (because neither the name nor the email matches), I will cancel the order.

Seriously, how hard it can be to monitor your PayPal, pay when asked to do so and make sure your name and address are correct? 99% of people can do it. That 1% that can’t really annoys the hell out of me. I’m done dealing with that.

UPDATE: A bit late but GDEMU orders are open now closed.

Electric Lion

I’ve been getting a lot of emails lately, so many in fact that I would like to remind you, dear customers, that this blog is here for a reason. I simply do not have time to answer each and every question about when device X will be for sale again, and can I put you on the list. There’s too many of you and one me. I tend to ignore emails with questions like these, not only for my sake but also because it wouldn’t be fair to all the other people who patiently follow the blog and wait for orders to open.

And speaking of orders, Phoebe will be available this Saturday, 18:00 CEST – to make this window more USA-friendly.

I still have some GDEMUs to ship and those should be ready by Monday or so. Sorry for the delay, I was hoping to get the PCBs in two smaller batches but instead I got a single big one, later than I planned. But I’ll have them tested and packed in the next few days so you won’t have to wait much longer.

UPDATE: Welp, that went awfully fast. This is the problem with USA-friendly ordering windows, a lot of people up and ready to click the button. As usual, give me a few days to process all this and send out confirmations.

Resource Deficiency

As I was waiting for the Phoebe PCBs I had the opportunity to work on a Commodore 64C board. I know next to nothing about those but I got the board cheap in rather sorry state and figured I’ll try to fix it – for the fun of it.

Long story short, the board does work now but it was missing the TV modulator so there was no video output at all, as on these later models the video amp is also a part of the modulator. So I had to come up with a replacement. Now, schematics for C64 are available and I wasn’t the first person with that idea but for some reason all the projects I saw on the net were using crude veroboard/wire based hacks, with very questionable component selection.

So here’s my take on this:

There’s no actual modulator in there anymore, just the luma+chroma amps based on low-noise high gain transistors. Both S-Video and composite signals are being generated. I’ve built two of these and now I’m looking for a C64C owner willing to test the other one. Note, this is only compatible with the C64 models equipped with the new VIC chip running from 5V!

What I offer is this here PCB, free with worldwide shipping. What I expect in return is a report from someone who has experience with C64 and it’s video quality – especially on LCD monitors – who can tell me if it’s acceptable or not. I think all these 300ohm resistor hacks in S-Video cables are unnecessary, but I need someone with better idea on what should be on the screen than I have.

Obviously installation will require soldering so if you have to ask, it’s not for you.

Rising Haul in Silence

Time for status update.

It took a while but I should be finally done with current DocBrown list next week. Those matte black soldermasks are a pain in the behind to work with. Need to be extra careful not to put any scratches or fingerprints on them.

On the bright side – I’ll be getting another batch very soon and so I will most likely open orders for these on first Saturday of April. I will confirm that later.

Now, Phoebes. Those got badly delayed (in part due to a nasty cold bug that’s been very active lately) and the finished PCBs will only arrive next week. Then I still have to inspect, final clean, program and test them, that’ll no doubt mean another week of waiting. Sorry about that.

It seems though the Brexit armageddon has been postponed a bit so I should be able to ship all UK orders in time. At least I’ll try to prioritize those. If you’re in UK and still waiting for your Phoebe then pay attention to your PayPal, the sooner you pay the sooner I can ship.

Because of all the delays I’ve decided not to open orders for GDEMU or Rhea yet, it only adds to my problems. Now that I’m almost out of the woods though I can plan for new batches so GDEMU orders will open next week.

UPDATE: GDEMU orders are open now closed again. It seems there was some confusion as to the time but it’s nice to have the emails flow in one by one rather than have a massive torrent at the exact hour. Oh, and before I forget, DocBrowns will be next week, as mentioned above.

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.

Discovery

I’ll be shipping whatever Type-3 Phoebes I still have in stock next week, and after that there will be a short pause until I get the next Phoebe batch. So if you don’t get payment request next week you’ll have to wait until the first week of March, or so.

Same goes for any DocBrowns I haven’t shipped yet. There was a delay with the parts I ordered and now the batch is about 3 weeks behind schedule. On the bright side those will come with 1.5.1 FW that has the Flash corruption issue fixed for good. Though if you had this problem with 1.5.0 and you haven’t recapped your Marty PSU yet, I’d recommend looking into it sooner rather than later. In general these PSU hold up rather well for their age but the electrolytic caps are probably only barely within specs by now.

Speaking of FM Towns, I’ve found some TI docs that nicely explain what external circuitry the 486SLC-class CPUs need to have proper cache flushing support. Considering that replacing the 386 with 486 usualy involves soldering anyway, additional wire or two and an extra 74AC chip wouldn’t really be that much of a problem and it just might simplify a lot of things on the modded system. I need to investigate.

It would be much easier (and cheaper should I mess up) to experiment on a typical PC mobo though, and so I’ve obtained one that looks like it can actually support 486SLC chips natively. But the clock is hardwired to 40MHz for the AMD 386SX that’s on it – and while it’s not terribly difficult to mod it to a different clock speed with external generator, I’m not sure if it’ll work properly with the memory and ISA bus. Chances are those have to be synchronized with the CPU clock.

So, if there’s anyone with a TX486SXLC-040 chip in PQFP-100 package for sale, I’d be very interested in buying it. Or trading for some ODEs if that’s preferable.

UPDATE: Forgot to make a photo of the mobo: