Space Ninja

Rheas are shipped so I will open orders for Wizards this Saturday (2023-02-04) at 20:00 CET.

Orders are now closed. Please give me a day or two to process it all and I will send out confirmation emails. Though I can already tell I have a problem, the stock I prepared was calculated based on the previous batch and it looks like this time there were more orders. I’ll let you know the details in the email but some of you might have to wait for your Wizard.

Body snatchers, contd.

I will open orders for Rheas this Saturday (2023-01-07) at 20:00 CET.

In other news, remember this device?

No, this is not another photo of it. This is a screen capture of an emulator running on my PC. Why emulate a multimeter you might ask – well I did explain before that it has an option for external interface but I don’t have it, and adding it would require updating the FW which is a set of 4 old EPROM chips in a very fragile PCB. So I’d rather make a new PCB with new part and the I/O module integrated into it, and then swap the whole logic PCB. Since I don’t want to use 8080 with it’s weird 12V logic and support chips I’d have to switch to 8085 (I actually have one), Z80 (have several) or just do it on a modern ARM Cortex MCU, preferably one with FPU so that I can have HW support for floating-point values (not really necessary seeing how 2Mcyc/s 8080 can deal with it in software, if only just).

So I’ve decided to emulate the 8080 to see how much work it would be to try and port that emulation to ARM in case I didn’t want to run a completly new code but rather emulate old FW but on modern hardware. To speed things up I decided to borrow Z80 core I made for Makaron and dumb it down to support only 8080 instructions (for emulation speed and to make sure I don’t accidently run Z80 code). This also helped me understand the FW much better, I now know how the A/D conversion works and how all the calibration data is used to make sure the device has the accuracy it claims.

Now the funny thing is I found a couple of nasty bugs in the Z80 turned 8080 core, makes me wonder just how many NAOMI games didn’t work right because of them. I might back-port the fixes some day just to check that.

And one more interesting bit, remember that Varta battery this multimeter used to supply the calibration NVRAM when power was off? The one made in Western Germany? Well turns out it was the original battery from the factory, I’ve replaced it recently and here it is desoldered with date code now visible:

October 1988, and it still holds nominal charge. Although these usually have pretty flat voltage curve right until they die, so it was high time to swap it anyway.

Body snatchers

Sorry for the long silence, I was very busy and after that I caught a pretty nasty stomach bug that made me miserable for over 2 weeks. Then I decided not to open orders because it would mean shipping in December and that’s a bad idea for small vendors like me. Too many things get lost or damaged in shipping because everyone rushes to buy gifts for Xmas. Next ordering window will therefore be open in January 2023.

If you emailed me in the last 2 months or so and I never got back to you, please email me again. I try to answer all mail but I don’t always have time to reply right away (or I need to check something) and, if I’m busy enough, I can then forget to reply at all.

Speaking of Xmas, a nearby business was cleaning their storage rooms and throwing junk away. So I scored an older PC, with monitor, for free. It was dirty and pretty yellowish but dirt can be cleaned and I don’t really mind the old plastic look. The important thing is nothing was cracked or broken, and the thing actually works too. Here’s a few photos (after the cleaning):

First the mobo, it’s a 286 system with Intel CPU (8 MHz, with 12 MHz turbo mode) with 1 MiB of RAM. I don’t see any way to expand the RAM other than EMS ISA card (which I don’t have and don’t really need). RAM chips are mostly 80ns so no point in trying to go 0WS on this board, it’s unlikely to be stable. There is a co-processor from AMD, and it’s rated for 10 MHz but the mobo has it clocked at 4.77 MHz and that can’t be changed without modding. NiCd battery did corrode and was removed but haven’t managed to do significant damage to the copper just yet – no repairs were needed.

This is a Hercules clone, a full-length ISA card by the way. Works fine.

MFM controller for HDD and floppy drives, a bit shorter then the Hercules. This PC has an extremly simple Award BIOS that doesn’t even support IDE HDDs. All you can select is one of the 40 predefined HDD profiles for MFM/RLL or use a SCSI card with it’s own BIOS.

Speaking of HDD, there is an ST-251 with a whooping 40 MiBs of magnetic estate. And not only it spins just fine, there are no sector defects – even the ones from the sticker ended up between sectors and are not affecting the operation. HDD surface was tested with SpinRite and, after some 12 hours, got a clean bill of health.

This is a pretty big 5.25″ drive so on the photo I’ve added a bit younger SCSI ST12550N for comparison – and by modern standards that one is also a big and heavy drive. BTW that SCSI HDD has SGI firmware in it and reports less available space than a standard ST12550N would. My guess is SGI wanted more reliability and opted for more hidden sectors for remapping any bad ones. Not that is has many of those but man, that disk is loud and requires good airflow or else it wil get rather hot. I’ve picked it for the photo because those two drives sure take their time to spin up (and down).

Here’s the monitor. It’s another monochrome CRT except amber this time, and the tube is pretty strong too. Obviously needed a full clean both outside and inside (I’m not afraid to remove the tube, it’s safe if you handle it properly) but it was mostly extremly dusty, no tobacco residue to clean this time. Which is nice for a change. This monitor is frankly even better then the Philips I’ve just shown, it can better correct for image sharpness in the corners and it accepts both 50Hz and 60Hz signals – though the green phosphor has longer glow time, which on one hand causes some ghosting in games but makes 50Hz text mode display flicker way less on the other, good for the eyes if you need to work with one.

Also this monitor can natively accept CGA RGBI signal, without needing a card with CGA-on-MDA emulation like what the ATI offers. Obviously there are no colors but shades (intensity steps) instead. Coupled with its ability to properly lock to CGA refresh rates (this monitor uses a dedicated chip for vertical deflection rather than a bunch of transistors) it gives you the option to use either MDA, Hercules or CGA card to drive it. Neat. And here is a sample of what the CGA colors-as-shades look like, I’d say it actually looks better then the terrible cyan/magenta palette):

I also scored some other free stuff, old SCSI HDD (78 MiB in 5.25″ package), 5.25″ double density floppy drive, some 3.5″ floppies, 15″ SVGA CRT monitor (tube is not virgin but still decent) and various other bits and pieces. If there is interest I can make some more photos. All this stuff means I don’t have to buy myself anything for Xmas, there’s already enough junk to play with as is 🙂

Atomic Wraiths, contd.

I’m almost done shipping Rheas, and Wizard testing is slowly coming along. In other news – I got notified that shipping to Australia is not possible at this time. Not sure why, I assume it’s COVID-19 related? Kinda forgot about that one but, as colder weather is slowly coming to northern hemisphere, we might all get a rude reminder very soon.

Speaking of colder wheather, I got myself a new space heater – obviously a used one, quite a lot too, but it was cheap. Didn’t need any repairs but I took it apart and cleaned it properly. Replaced one capacitor I found to be a bit tired. The rest didn’t look too bad so I kept them all original.

The hue of the green is off in the photos, in reality it’s not “radioactive green” but a darker shade (as in, more green than green-cyan). Eyes perceive it differently than camera sensor, I didn’t bother trying to rebalance it. Strictly speaking this is a monochrome monitor with TTL inputs for video and intensity signal – so at best you can have 4 brightness levels including black. Obviously a PC Hercules card in graphics mode can only do 2 levels, on or off, you can do “shades” by dithering pixels since the resolution is pretty high – 720×348.

That being said I have ATI Graphics Solution card that can drive a mono (MDA/Hercules) or color (CGA) monitor, and best of all, it can emulate CGA on mono monitor, and MDA on CGA monitor – including CGA composite mode except without making the pixels fuzzy like an NTSC TV would. Haven’t actually looked at the signals with a scope but I suspect they are modulated per pixel to get 8 different brightness levels. This does have some limitations but works in general. Spot the differences in “CGA” screenshots below:

Working on older electronics is fun. These days if something breaks you might as well throw it away, it’s just a bunch of chips barely visible to the naked eye, and potted/glued so can’t even be opened. I guess I’m getting old because, while I sure enjoy my CPUs and GPUs and super-duper HD flat panel displays, I still miss the old days…

Atomic Wraiths

I’m almost done with DocBrown queue – I will have a few units left so if you missed the ordering window last time but already have Marty and can provide the serial number, please write in comments. If you don’t have a Marty (yet) just wait for another ordering slot later this year.

I will open orders for Rheas next Saturday (2022-08-20) at 20:00 CEST. I have some Wizards too but those need to pass testing first, and that is a lot of work for me. I hope to have them ready soon.

Speaking of testing, every now and then I get asked about ODE for the desktop Towns models. Well, somehow I’ve managed to misplace the prototype PCB. I damaged some chips, had to replace them, eventually damaged the PCB too, then it got lost somewhere. I have no idea where I put it…

So I made another out of Wizard prototype board with some extra hardware and wires. It kinda works now but is not very stable so I’ll probably need to design and order a better PCB. This should help with signal integrity – frankly though the Fresh machine is the hardest yet to get the ODE working. Possibly because it’s original drive is x2 speed capable and the chips expect different timings. I still hope to resolve these issues with software tricks to keep the hardware simple and reliable. Here’s a photo of what the current prototype looks like:

UPDATE: Rhea orders are now open closed. Give me a few days to process the orders. As for DocBrowns, I did say I have some left but not many. If you didn’t get an email from me then you’ll need to wait for the next batch to order. I expect it will take at least 6-8 weeks to make and test a new batch.


DocBrowns are finally here, orders will open this Saturday (2022-05-14) at 20:00 CEST. While sending confirmation emails for Rheas I’ve noticed that my email provider is again being blocked/bullied by some sites, no doubt to force me to switch to more “reliable” service. At least this time I got notified of the block, and the offenders are and Keep that in mind if you use those because I ask for Marty serial numbers and if I’m blocked you will not be able to see and answer my request.

And now time for some random photos. I got a new (well, new to me) toy for some 50 EUR shipped:

It’s an M1T 380 multimeter from Metra. In theory it offers 6 and 1/2 digits in VOLTS/AMPS when using rather slow (~2s) HI.RES mode, in reality I might have to mod it to provide better temperature stability (noise doesn’t seem to be a problem, not as far as I can tell – I’d need a modern and calibrated meter of this class to compare with), but the good news is some people already tried that with good results.

As you can see it was made in Czechoslovakia, behind iron curtain. So while the date says December 1988, the inside resembles very late ’70 or early ’80 western electronics. Back in the day we had to work with what was available. And that became very apparent once the meter arrived – there was no power cord and it seems Czechs/Slovaks back then used their own standard of plugs called Typ 5813 – that thing is still made out of bakelite. Wasn’t easy to hunt that down and I didn’t want to replace it with modern IEC socket if I could help it – but I’ve managed to order two NOS plugs from and I made my own cable.

This is a 380.0 model, meaning no external interfaces, something I intend to change. I’d like to have a modern USB, or at least RS232 port (especially since it would offer full control over the instrument). I have a manual and full schematics – it’s all in Czech (which I don’t speak, not to mention all the technical terms) but I get enough of it not to be completly lost.

Seems to be in working order, after some cleaning and fuse replacement. One of the tantalum capacitors died and shorted after a few power-ups, that can happen with the old “teardrop” types. It was a bit annoying the cap in question was a part of the input chopper amp module, it’s a separate black box (no, really, see photos below) on A/D converter board that I had to desolder to even get inside. I’ve seen this entire box being replaced with a single modern OpAmp, might just do that too eventually.

The digital part is based on 8080 clone. Yup, not even 8085 (or Z80, which would be already considered somewhat obsolete in ’88). It’s probably because it’s a clone and was manufactured locally in many eastern bloc states, so much easier to source. There’s 1024 bytes of static NMOS RAM, plus more expensive CMOS RAM (256×4) to store the calibration data. This NVRAM setup uses 3V lithium battery to provide power when the meter is off, and for that you need CMOS tech if the battery is to have any reasonable life time. And get this, the battery on the PCB was manufactured in Western Germany (so even accounting for shelf time, it was installed there sometime in mid-90’s) and still measures over 3V. Yes, it will be replaced eventually.

The ROM is 8KiB (4x 2716 EPROM) and pretty much full. I’ve built a cable to interface with this board and dump the ROM (and calibration data), I’m slowly progressing through the disassembly. I opted to use Z80 mnemonics since I don’t really speak original Intel 8080. And the code, to fit into this space, has some hacks in it, and some bugs too, which doesn’t make it any easier.

The idea is to add the external interface board based on original schematics of that add-on module. There is a dump of the 2KiB external ROM of extra 8080 code for the RS232 board but I’m not sure it will work properly with my FW. I’ve compared it to the v3.6 which is known to work and there some patches in places where the REMOTE function takes over, so that might be a clue I need a FW update first. And removing these 2716 chips is not something I’m looking forward to, these PCBs are extremly fragile. Super easy to rip vias or traces.

So perhaps I should create my own CPU board instead with the RS232 interface already on it, I could fit all of it by using Z80 in place of 8080 (with a few tweaks to the timing-critical code) and modern RAM/EEPROM (or Flash, or even just EPROM) chips. This also saves me from having to work around another Czech-specific socket/plug combo that is unobtainium (that green one near PCB edge) and have just one PCB and some wires to the plug on the back of the unit.

Or, and this is something I’m seriously considering now, do away with Z80, put a modern Cortex-M MCU there. Run either my own code (after I figure out the complete protocol to control A/D board), or the 8080 code in emulator, or a mix of both. I could probably fit all of that in 5V compatible M0 part + MAX232 for the serial port. Or perhaps use M4F with hardware FPU, a few more chips to translate 3V3 to 5V, and code a few more functions like sliding window filter for example.

So anyway, as you can see it works but somebody messed with calibration and it was way off (this should be showing 10.00000V). I’ve already re-calibrated the DC ranges for VOLTS and AMPS, as well as OHMS – and now I’m testing my new toy for temperature and short-term drifts.

UPDATE: DocBrown orders are closed. I will process the orders and send out confirmation emails in 1-2 days, though I can already tell there’s a lot. I probably don’t have enough stock at the moment. I will have more but that will take 2 months or so, I’m planning on doing Wizards next and that takes a lot of my time.

Also Sprach Zarathustra, contd.

Rheas will be available for ordering this Saturday (2022-04-30) at 20:00 CEST, just like last time.

DocBrowns will come next, I already have the PCBs but there’s still some final cleaning, programming and testing to be done – so most likely early to mid-May. As usual I will announce the ordering window at least a few days in advance.

UPDATE: Rhea orders are now accepted closed. I will process the orders and send out confirmation emails in a day or two.

Also Sprach Zarathustra

I had plans for February and March. But there was the another COVID-19 wave and various shipping delays, and now ruskies decided to get genocidal again. No plan survives contact with the enemy as they say.

DocBrowns are still in production but I should have a batch ready in April/May, and then we are going to make some Wizards. Assuming I didn’t make a mistake (and none of the suppliers did either) and we have all the parts now. I might have a batch of Rheas in the meantime as well, these are mostly PCBs that originally failed testing due to soldering issues and have now been fixed.

I also have a small batch of Phoebes that I will most likely sell soon, not sure if this next Saturday or next the one after. Watch the blog I guess, I will announce it at least a few days prior. No GDEMUs yet though – I’m not sure if it’s Intel doing after they gobbled up Altera or what, but the FPGAs I’ve been using are unobtainium. I was considering a HW refresh, with more modern (and capable) parts that were actually cheaper, but it looks like these are gone now too. 50 – 80 weeks for delivery is not a time I’m prepared to wait. So there’s yet another idea, another redesign, but that one exists mostly in my head so far. I would like to try and make some more though, even if it takes another 6 months to finish and test the prototype.

Regarding ordering in general, I will no longer accept orders from or ship to Russia. Not sure if it’s even possible at the moment but I’m not going to hide behind temporary postal restrictions. That decision was mine. For now I’m also suspending shipping to China (including HK), this is due to various lockdowns that cause my packages to be badly delayed, damaged or even lost. I really don’t want to deal with that right now, especially considering already long shipping times and language barrier. So this suspension will stay in place until the situation gets better.

UK customers, be aware that there’s more customs checks taking place now for anything coming from EU, which means you might end up paying some duties or taxes – this should not happen with the declaration stickers I use but who knows. As far as I’m concerned there is no logic in brexit, it’s meant to be chaotic neutral, for better or worse.

Shipping inside EU will work as before, no issues, except it’ll take more time to process your payment (1-2 days or so) because of the changes to VAT rules. No next day shipping, not that I ever promised that but I did try in the past.

And lastly, this Phoebe batch should be unaffected but anything after might see new pricing. Everything is more expensive now – parts, PCBs, shipping costs. That hasn’t been decided yet but it is getting harder to find free time and motivation to keep this going. We’ll see I guess.

UPDATE: To clarify, because the way I wrote it was rather confusing and it’s not an April Fools joke, just me not realizing tomorrow is Saturday as well – Phoebes will be available either next week, or the week after that. I would not announce ordering window merely hours before it would be opening.

UPDATE 2: Phoebe orders will open this Saturday (2022-04-09) at 20:00 CEST to make it more USA friendly.

UPDATE 3: Orders are now accepted closed. Please give me a day or two to process the orders and then I’ll send out confirmation emails.

21st Century Common Man, contd.

Rhea orders will open 2021-10-09 (this Saturday) at 12:00 CEST (noon). In case some unforseen disaster strikes again and I miss it, please come back the next Saturday.

UPDATE: Rhea orders closed.

UPDATE 2: All Rheas have been shipped, and I have a batch of Phoebes almost ready. I will open orders 2021-10-30 (Saturday) at 21:00 CEST (that’s 9pm) to make it a bit more USA friendly.

UPDATE 3: Phoebe orders closed.

21st Century Common Man

Phoebe orders will open this Saturday (2021-07-31) at 12:00 (noon) CEST. It’s not a big batch but last time it was enough for everyone who ordered.

Wizards sent to Japan and South Korea took their sweet time getting there but should be delivered any day now. Something related to Covid or olympics maybe? Vertical connectors will be available very soon and I expect to resume shipping all the remaining units sometime next week.