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Hatari macOS nightly builds

June 19, 2017

For a few years now I’ve helped out the excellent Hatari Atari 16/32 bit emulator project with macOS builds. However, the Hatari release cycle is about once every year and I’ve myself noticed that the developments that take place in between are very useful and so I’ve sporadically made development builds available as well. Sometimes. When I’ve felt like it.

Of course, I can do better. While I don’t have a 24/7 macOS server running, and thus can’t completely automate a nightly build setup, my laptop will now try to produce new builds (whenever the source repository has changed) during other usage and publish them here: Hatari macOS nightly builds.

Please let me know if you find this useful, and if there are any changes I could do to make it even better.

The tale of high density Atari mystery

January 20, 2017

The Atari ST, like other computers at the time, had Dual Density disk drives with 720KB of storage. DD for short. Since High Density (1.44MB) appeared shortly after, Atari used such drives in the more top of the lines models Mega STE and TT. Additionally, us enthusiasts and hardware hackers added HD capability to the regular ST and STE range since it was neat to store twice the amount of data on suitable disks (and it worked pretty well cutting a hole in DD disks tricking the drives into thinking they were HD, even though the magnetic layer is slightly different).

All the above is of course very well known. However, recently I’ve managed to dig up some less well known information as well as adding new discoveries about our dear 30 year old hardware. This is a post about that.

Atari used several different makes of DD drives in the ST computers, but one of the more common is the Epson SMD-380. For the higher end models with HD support Atari however used one model exclusively, the Epson SMD-340. For after market HD modifications of ST:s one drive in particular became quite popular, the Sony MPF-920. If you search online for kits and instructions, that’s the drive you’ll find the most info on.

It’s not only the drive that decides whether to write in Double Density or High Density however. The data needs to be clocked faster through the drive onto the disk, and so it’s not enough just swapping in and out the drives mentioned above to choose between DD and HD support. A neat little trick is that the floppy controller used by Atari, the 1772 (made by WD and VL), outputs a DD capable signal when clocked at 8MHz and HD when clocked at 16. In a regular ST it’s always clocked at 8MHz, and in the Mega STE and TT Atari used carefully tested chips that could do 16MHz (and later elected to produce a variant themselves, known as the AJAX chip, that was designed to run at 16).

The way to get HD support in a regular ST is thus to clock the floppy controller at 16MHz when writing/reading an HD disk. I might be misremembering, but I think my own first HD mod needed manual selection through a switch and so I needed to select the right position depending on the disk I used. A much better option is of course to ask the drive if there’s a DD or HD disk inserted, and switch clock speed depending on that. This is what’s well documented for the Sony MPF-920 and is how the many different “HD kits” know what to select.

Now here’s where things start to get confusing. In many places you can find documentation to the effect of pin 2 of the floppy interface being a density select signal. An output. While that might be true for some drives, my research says that it’s an input. The Atari Mega STE and TT (the Epson 340 drive) does not get told whether there’s an DD or HD disk in the drive, and yet they still have full support for both formats. This part of the mystery took me to an old discussion thread from 2008 which seems to be the first time someone actually looked into how this was done. There’s a memory mapped register, handled by a PAL chip, that the Atari operating system (TOS) writes to to set the clock frequency of the floppy controller. The logical conclusion is thus that TOS switches frequency when encountering errors and retries.

In that sense, the after market ST mods did a much better job. The drive told a piece of circuitry what it should use and the clock frequency was then set correctly. Many many ST top cases have been horribly butchered to make room for the normal eject button of most HD drives instead of Atari’s nice slanted cutout.

Of course, I wanted to make my tricked out STE (see other posts) read HD disks as well, since I spend a lot of time archiving lost treasures and sometimes come across HD disks. I did not want to butcher the top casing though.

Idea: Use the same HD drive as Atari. The front plate and eject button of the Epson 340 and 380 are interchangeable, and the Epson 340 can still be found used online (and after some digging I found that it was also sold by Hewlett Packard under their brand as D2035-60011). I also bought an HD-kit from exxos that seemed to handle some obscure effects (steprate issues) adding HD to ST:s can cause.


Here’s where I realized that although it’s easy to find where to pick the density detect signal on other drives (like the Sony) absolutely no one seemed to have ever done it on Atari’s HD drive of choice (!). After some measuring and tracing I found the spots to use, and although the drive can be set to handle density internally I also only got it to work if giving the drive its own density detect signal as input on the density select pin #2, and told it to use the external signal (jumper 1-2 & 5-13).


Since I have two drives internally (an HxC and the internal floppy) and a switch to choose which is A: and B: respectively, I also had to create a logic table on which signals should select which input and density. The result was (disregard the wiring on the image, I don’t seem to have one from the final conclusion) that the kit should get post-switch signals and D1 should get density detect from the drive. With all this done, my STE now has full DD and HD support – with a beautiful and newly refurbished Epson 340 as the internal drive. I save my case cutting for LCD displays, SD card slots and USB ports ;)

DD: YM DS0 —— no switch —— HD-kit DS0 —— cable DS0 (8MHz) = floppy A:
DD: YM DS1 —— no switch —— HD-kit DS1 —— cable DS1 (8MHz) = HxC B:
DD: YM DS0 ———— switch ———— HD-kit DS1 —— cable DS1 (8MHz) = HxC A:
DD: YM DS1 ———— switch ———— HD-kit DS0 —— cable DS0 (8MHz) = floppy B:

HD: YM DS0 —— no switch —— HD-kit DS0 —— cable DS0 (16MHz) = floppy A:
HD: YM DS1 —— no switch —— HD-kit DS1 —— cable DS1 (8MHz) = HxC B:
HD: YM DS0 ———— switch ———— HD-kit DS1 —— cable DS1 (8MHz) = HxC A:
HD: YM DS1 ———— switch ———— HD-kit DS0 —— cable DS0 (16MHz) = floppy B:


(Oh, and since Atari had their own way of handling media change detect – knowing when a new disk had been inserted and you needed to re-read the FAT – a lot of disks have been trashed from the use of non-compliant drives. The exxos kit above has an optional workaround in that it always forces a re-read, but the best solution is of course to use the same HD drive as Atari did, and not having to use any media change workarounds at all)

Fountain of Youth – the two month update

December 26, 2016

Today it’s exactly two months since I started on my “Elysium Basis” regime. Since quite a few of my friends have asked me to write an update on my thoughts about it – here it is.

I’m still of the opinion that I have more energy. I’m also confident in the “smoother skin” effect, although I’m unsure as to whether it’s because it actually is or if I just, for some reason, experience it to be.

Just as before I’ve stayed away from researching what effects I should/could expect, only looking them up once I’ve noticed a change to see if others might’ve as well. And so the third thing I’ve noticed so far is …

Alright. Before I write this I need to make a disclaimer: The effect is very slight – I do not think it will become noticeable to anyone but myself. I’d hate for anyone I know to rush out and by these supplements just because of this blog post, so please, don’t.

With that said, I seem to have some hair regrowth where the hairline has receded over the last decade. Some. A little. Most likely not noticeable if you don’t, like me, see my face in the mirror every day.

Now on to the negatives, if they are. I think my energy levels are lower than what they were a few weeks ago. I also have some “body ache”. I’ve seen others claim that this could happen if you have a methylation pathway problem, and indeed I do. Thanks to “DNA-testing” (SNP, through 23andme and Genetic Genie) I know that I have homozygote mutations affecting my methylation. I’m not sure what to make of this, currently I’m waiting to see if it gets better/worse. Since I suffer from SAD I also know better than to make too much about what I feel during the darkest months of the year (I’m no longer on SSRIs as described in that post).

tl;dr: I’m still taking NR+Pterostilbene, and will continue to do so for the moment.

Fountain of youth

November 3, 2016

“it’s better to burn out than to fade away”

(From Neil Young’s My My, Hey Hey – and known for being quoted by Kurt Cobain in his suicide note)

I remember my teenage years well. I also remember voicing the opinion above, along with other things along the lines of “life ends at 30”.

I’m 42, almost to the day. I have no intention whatsoever of fading away. I consider myself a transhumanist, and I spent some time being a board member of the Swedish subcategory of Humanity+. I subscribe to the idea of aging being just another disease we haven’t cured yet, and I eagerly follow the current state of research on the subject.

One development in particular, popularised by the company Elysium, is a combination of substances that counteracts one of the possible sources of a lot of age related problems, the declining quality of communication between our cell nucleus and the mitochondria that powers it. The list of things this affects (effects, even) is quite long – and for quite some time now there have been promising tests on yeasts and mice on how to counteract this decline, in effect boosting the levels back to where they were when we were younger.

A few weeks ago the results of the first clinical human tests were published, and I am since five days on the same formula as Elysium sells under the brand Elysium Basis. It consists of 250mg of Nicotinamide Riboside, taken together with 50mg of Pterostilbene, once a day.


… and I’m quite stunned, at the moment. I’ve carefully avoided reading too much about what effects I should experience, instead going at it with the outset of trying to see what my general experience of a month’s usage would feel like compared with before. I know all too well how dangerous expectations (and the placebo effect) can be when trying to evaluate something like this.

However, even after just a few days one effect stands out so clearly that I have no doubts whatsoever as to its existence. My general energy levels are up, way up. This applies to everything from feeling more awake directly in the morning, to walking at a very brisk pace to the bus station without feeling the slightest need to increase my rate of breathing, to working through the day and yet being fully energetic when coming home to play with my children in the evening. This does not in any way feel artificial (like you would get from Modafinil, for example), I just feel … more capable.

(Another possible effect, although I only noticed it a day ago, is that my skin feels … smoother, softer. Like after having used a facial cream after shaving. I’ll have to get back on how certain I am of this later)

So why am I taking these supplements? Is this just a case of death anxiety?

Well, I don’t think so. I do however know both from my immediate family members’ medical history, as well as from DNA testing, that I would be wise to take care of a few things that otherwise could become issues. I would consider right about now to be a suitable point in time to start making sure that I will keep my health into my 50’s, 60’s,…, 100’s.

Increased cardiovascular health, better neuro protection and lowered blood sugar levels is what I’m aiming for. Live long and prosper. One (two) pills a day.

Mega STE 1.44 HD floppy, FPU, fan and RTC upgrades

July 14, 2016

A few weeks ago I acquired a computer I never had the chance to play around with when it was new, an Atari Mega STE. It’s the culmination of Atari’s 16 bit line of computers, very compatible with the ST(E) range yet much more expandable, usually coming with a SCSI adapter and HD (1.44MB) floppy support. Besides the expandability, it can run at 16Mhz, with cache, compared to 8MHz for the rest of the ST(E) computers. It also has a socket for a 68881/68882 FPU.

However, a few very early Mega STEs didn’t come with 1.44MB floppy support, and there aren’t really any Atari dealers left if you want to sort that out – or for that matter add the logic chip needed for the FPU. So, during the last few weeks, I’ve sorted out what needed to be done to get the machine “up to spec”.

1) I found a wonderful guide over at D-Bug’s site on replacing the (VERY LOUD!) PSU fan with something almost completely silent.

2) I realized the mythical Epson 340 floppy drive (Atari’s HD drive of choice) was also sold under the HP brand as Hewlett Packard D2035-60011, and snagged two quite cheaply off Ebay. The big benefit of using the Epson is that you can transplant the eject button and faceplate from the old 720KB drive and thus no modification to the casing is needed.

3) After some searching I found GAL files for both 1.44MB floppy support and the FPU support, and thanks to a fellow retro computing enthusiast (hi joska) I had both chips programmed. See below for more detail.

4) I figured out that there was a cheap and easy replacement for the original RTC battery – see separate post.

5) TOS 2.06. Yes, my machine came with 2.05. This was by far the easiest part ..

I really only bought the machine to be able to test compatibility with my software, I already have both a very tricked out STE as well as a heavily upgraded Mega ST, but I’m getting to appreciate the Mega STE more for every day. Maybe I need to have three different Atari models at my desk at all times?

Additional details for the curious:

FPU upgrade. As can be seen in Atari’s official installation manual most motherboards come with a jumper W3 that should be opened when you add an FPU. My motherboard didn’t, since it’s an older revision. According to the manual there should then be a resistor on the bottom side of the motherboard that you need to remove. At first I thought mine had already been patched, since a resistor was placed in the socket topside – but due to needing to do something else on the bottom side later (see below) I found out there indeed was a resistor there as well. Remove, insert the C301903 GAL, insert FPU (a 68882 in my case), test with Gembench 4.03 and everything’s fine.



HD floppy upgrade. After purchasing the Epson 340 (HP version) and transplanting the faceplate and eject button, I replaced the C301901-001 PAL with the newly programmed C301901-002 GAL code. See Atari’s official manual for details. Naturally my motherboard was again of the very old revision indicated and there was no continuity between U7 (the CPU) pin 32 and UA2 (the GAL) pin 19. This was why I had to turn over the motherboard and make that patch. After that all that’s needed is to change dip switch number #7 to on and test the new HD floppy support. Recalling common knowledge from way back then I didn’t bother to exchange the floppy controller to the AJAX model, since it was a WD1772-0202. Other WD-models might be more of a hit’n’miss whether they can handle 16MHz or not.




How to config an Airport Extreme from Linux

June 6, 2016

This weekend is a long weekend in Sweden – and of course I’m away from home, hacking away at the infrastructure I’m far away from. During that hacking I needed to change a mapped port in my router, and suddenly realized I couldn’t. I use the latest Airport Extreme (it really has the best performance, throughput as well as wireless stability) and the only machines I remote into are Linux (Ubuntu 16.x) based.

Conundrum. To begin with I feel this is quite lazy of Apple – they have software for not only Mac and iOS but Windows as well. My previous home server was indeed a Mac (Mac Mini, 2007 model) but since Apple no longer supports it with security updates I had to change. Linux feels more future proof. But I digress.

There’s apparently an old Java based library to interface with Airport Extremes, but not only does it rely on outdated Java versions, but it’s also very limited in what configs you can change with it. The other alternative is of course to see if Wine works.

Which it does. However, I did not get it to work at all first – nothing happened after installation when I tried to run the config app. Luckily someone else had already figured out that if you’re on 64-bit (and let’s face it, we all are today) you need to explicitly use Wine in 32-bit mode for the Airport Extreme config application to work.

Tada! Port mapping changed.

Overscan and sync scrolling

December 23, 2015

This last weekend me and many others were participating at the third incarnation of the STNICCC Atari ST conference. The first and original one was held in 1990 – where sadly I didn’t attend – and the second one was held as a reunion in the year 2000. Back then they joked about meeting up again in the far far away future of 2015.

… and that happened. Me and two others from my old demo crew had written a brand new demo that we showed at the demo competition, and additionally I had been asked by the organizer to do a talk on the latest findings with regards to two of the Atari ST’s more magical demo tricks – overscan and sync scroll.

The talk was recorded, and I’ve uploaded a version where I’ve tried to clean up the audio to Youtube. My slides (even the final version which I was unable to use during the presentation) can be found in the video description.


update 2015-12-31: I mention in the talk that I will release source code showing how you can detect the wakestates yourself. Now done. Pre-built binaries here and code on Github.