Mildred's Projects Thread

[MildredHubble]

Since I've been working on a few things recently and I seem to have the energy to make decent progress lately, I thought I might start a thread where I try and show what I've been doing and hopefully maybe one or two people might find it interesting.

I've posted about modifying 3rd Generation iPods in another thread, but I think I will post here from now on as and when I make stuff

So for my first post I thought I would try and show how I built a PiStormSTE accelerator for my Atari STe computer. This device will plug into the space where the processor usually lives and a single board computer known as a Raspberry Pi will emulate, or pretend to be a processor instead.

The Atari ST is a computer that was released in 1985 and is considered a 16bit computer. It was pretty powerful back then but it didn't really see much in the way of upgrades at the time. So it's kinda fun to see these machines achieve what would have been ludicrous back when it came out

So this is Part 1 of building a PiStormSTE. Sorry the photos aren't great. I'm just figuring out how difficult it is to photograph these sorts of things! I have a new found appreciation for people who do this sort of thing on YouTube!

This is the printed circuit board I will be working on

I didn't design this myself, instead I ordered it from the community projects page on PCBway. They manufactured it and posted 5 boards to me. So I have 5 opportunities to get this right! I chose to have them made with a white solder mask as I thought it would look cool really

I decided to start with the 4 chips labeled U2,U3, U5 and U6. I usually start by lining the chip up with the solder pads and then carefully solder the pins on opposite corners the fix the chip in place to make it easier to solder the rest. I use a cheap microscope connected to my laptop so I can see everything better and hopefully won't end up with tons of accidental solder bridges that would cause shorts. I took the pictures from my microscope as I thought they would be best but upon reflection, I think I should have tried something else.

So this is my first attempt with the first chip...

I started by brushing on some flux which helps the solder to flow better onto the contacts on the board and the pins on the chip...

The picture is a bit rubbish but in the bottom left corner you can see the tip of the soldering iron applying some solder to fix the chip in place.

Once that was done, I could drag the solder along each pin and enough to make a connection would be applied to the pins. You need to keep adding a bit of flux as you go. Sometimes you might bridge two or more pins together and you have to remove the solder with desoldering braid which wicks up the excess solder.

The desoldering braid is just woven copper wire and you lay it over the joint with excess solder and gently press the tip of the soldering iron to it and as the copper heats up the solder beneath becomes liquid and through capillary action, gets drawn into the braid. You have to be careful to maintain heat as you move the braid away or it can become soldered to the board and rip up the chip and contacts with it!

The flux makes an icky, horrible, brown sticky mess on the board, but after you clean it up with some alcohol and a toothbrush, hopefully you see a pretty nicely soldered chip on the board with no shorted out pins!

Here I repeated the same process with the chips at the top right of the board. These went on a little easier than the others. The 4 chips I started with seemed to soak up the heat from the soldering iron and made the process a bit frustrating, but these were nice and easy.

Next was the big square chip labeled U4. This one is theoretically the hardest to do as you have to line up the pins on all 4 sides! I use the same method as the other chips still, and you can see I'm just tacking down the pins on the top right (kinda, I need to improve my photography method in the future!).

So under all that flux residue, the drag soldering process is actually going really well! I guess I got lucky, but it was perfectly lined up and a little desoldering braid was used to tidy up any solder bridges like before.

Next I soldered this voltage regulator. It didn't go on very straight, so that's going to annoy me every time I look at the board lol!

I will have to continue in a second post as I can only attach 10 photos...

 

[MildredHubble]

.... Next I soldered on the pin headers. These will make the connection to the Atari ST processor socket (arranged in a square on the right of the board) and the other row (top left) will be where the Input/Output pins from the Raspberry Pi will connect.

Next I connect up the super easy components, these are the capacitors and resisters labeled as C1 or R1 and so on. Usually I add some solder to the connection on the board and heat it up with the soldering iron and use some precision tweezers to place the components. Then I remove the iron while holding it in place with the tweezers. Then I can solder the opposite connection and tidy it up a bit.

So that's everything soldered in place. I'm happy enough with the straightness of the components I guess. I prefer everything to be super straight but I will go mad trying to get it perfect and risk causing damage.

And there we have it! The finished board! Of course it had to be scrubbed clean with some alcohol etc, but I think it looks pretty good! All this took me hours though, I used to be faster but I will sacrifice speed for precision. My back and arm pain gets in the way unfortunately so I need lots of breaks. But with practice you could probably whip up a board like this in an hour

So next post will probably be of me programming the board. The square chip in the middle is where the magic happens that makes this all possible. It's known as a CPLD (Complex Programmable Logic Device) so in order for it to work it must be programmed first. Fortunately this will take place on the Raspberry Pi side of things. So I will try and show that in my next post!

Well I hope that wasn't too boring or awful to get through! Thanks for taking a look if you got this far and I hope it was all at least somewhat interesting!

 

[Slime_Punk]

Yay, Pi projects! (or projects that will eventually involve one!)

Looking good so far! Honestly, if I saw that board out in the wild I would just assume it was a professional job! Have you considered adding a few videos to the experience? I'll be along for the ride either way, but I could see that drawing some more spectators in. Keep up the good work and I'm excited to see what happens next

 

[MildredHubble]

Yay, Pi projects!

Looking good so far! Honestly, if I saw that board out in the wild I would just assume it was a professional job! Have you considered adding a few videos to the experience? I'll be along for the ride either way, but I could see that drawing some more spectators in. Keep up the good work and I'm excited to see what happens next

Awwww thanks @Slime_Punk I do try to do my best when soldering so I'm glad you think it looks good! It's difficult to know when you've done it yourself if that makes sense? You think others are going to look at it and find tons of faults lol!

I have considered the possibility of doing some videos. I think static photos don't really tell an elaborate story about the process. The reason why I didn't go straight for videos is that I thought it would be really difficult to get right, and also, I don't like the idea of talking in videos. Not for me, but I guess I could use captions!

I'm glad that you find my project interesting! Hopefully the actual installation and using it will follow fairly soon!

 

[Aspychata]

Of course the worry wart l am has to say, please solder in a well-ventilated place if it's similar to stain glass, because the flux is poisonous to breathe in.

 

[Angular Chap]

Your surface mount soldering skills are on point! I'm jealous!

 

[MildredHubble]

Of course the worry wart l am has to say, please solder in a well-ventilated place if it's similar to stain glass, because the flux is poisonous to breathe in.

You are quite right @Aspychata Don't worry, I do have a well ventilated area to work in

Your surface mount soldering skills are on point! I'm jealous!

Awww thanks! I don't really show people my soldering so it's kinda difficult to guage if I'm doing it well, particularly when it comes to surface mounted components. Through hole components are a bit easier to judge!

 

[tazz]

This is cool.

I got my STe modified a couple of times. First, I bought a RAM extension which was just some chip that you pushed on, piggybacking off the original chip. It kept popping off so I ended up building some contraption around it to clamp it in place. Second, I found some guy online who owned a pet shop specializing in lizards. On the side, he would do some 'lectronic wizardry to enhance games consoles and computers. I don't actually recall what he was trying to do - but it didn't work right so I had to take it back and ask him to remove whatever gizmo he attached. Anyway - not in the same league as your handywork @MildredHubble

 

[MildredHubble]

This is cool.

I got my STe modified a couple of times. First, I bought a RAM extension which was just some chip that you pushed on, piggybacking off the original chip. It kept popping off so I ended up building some contraption around it to clamp it in place. Second, I found some guy online who owned a pet shop specializing in lizards. On the side, he would do some 'lectronic wizardry to enhance games consoles and computers. I don't actually recall what he was trying to do - but it didn't work right so I had to take it back and ask him to remove whatever gizmo he attached. Anyway - not in the same league as your handywork @MildredHubble

There were quite a few upgrades that piggybacked onto the CPU or RAM. They were mostly designed to be fairly easily installed by end users but they did have a habit of coming loose. Just a mild shock to case, for example lifting the machine to plug in a mouse or joystick into the Atari STs poorly placed DB9 sockets, could dislodge them.

This PiStorm uses a similar approach to be fair, but you have to remove the original CPU. It doesn't sit wedged between the chip and the socket, it just plugs in to the empty socket.

I may have to consider 3D printing a bracket to keep it in place as with the weight of the raspberry pi, I'd imagine it will be prone to moving. But once I'm testing it out, I may just hot glue the board to a nearby screw post temporarily

 

[MildredHubble]

I've been working on something. I haven't gotten round to installing my previous project into the Atari STE yet as I've hit a snag with a previous modification I made to it and I'm not entirely sure of how I did it (It was a ROM OS switcher) so I need to reverse engineer my work first lol!

In the meantime, I was rather spoilt at Christmas, I received a ZX Spectrum N-Go board. For anyone that doesn't know, the N-Go is a clone of the latest version of the British 8bit computer, known as the ZX Spectrum Next. It's very expensive, but a clever person made a clone, which is actually something the ZX Spectrum Next team encourages.

But I just had a bare circuit board, no case or keyboard. The cool thing is that with a bit of modification the N-Go (or Next) will fit into an original Spectrum case and you can wire up the keyboard and it will work.

So here is a preview of what I've been doing if you are interested. It's not a particularly exciting picture, but the N-Go board is in there. It's originally a Spectrum +2 case with a built in cassette recorder for data retrieval and storage! This one won't be a build log perse, but I will be including some pictures of the mods I've made to make it all work soon! So if this looks interesting, stay tuned!....

 

[MildredHubble]

Some more pictures of my progress I'm not doing this in a particularly precise way. I'm just kinda figuring things out as I go along. To me right now, the important thing is that I get the N-Go board fully integrated into the case in a way that without much trouble it could be taken apart again. I've used a fair bit of hot glue. I tend to avoid mounting things with hot glue but it's not so bad and with a bit of rubbing alcohol, it's fairly trivial to remove. If I get too obsessed with designing bespoke mounting brackets etc, I will never just get to enjoying using the machine lol!

Here you can see the board mounted in the case. As the N-Go has it's expansion bay (the row of gold contacts in the centre running to the right) in basically the same position as an original Spectrum and it's power socket (little black thing at the very top right) in the same position, all I had to do was line those up with the correct openings at the back of the case. I could then mark the positions of the screw holes using the board as a template. Then I drilled a small hole in each of the positions I'd marked, then I took some brass screw posts and by using my soldering iron and a little downward force, the screw posts were heated up until they melted the surrounding plastic and were strongly fixed into the bottom case.

The Spectrum +2 keyboard has the correct ribbon connections, but they don't stretch to the sockets on the board. I found I could connect one of them if I was careful, but the connection on the right of the board was too far away. So I soldered some wires to the connector on the reverse of the board and soldered them to a ribbon socket. You can see it poking out from the bottom left of the N-Go board. It's a bit messy but it works and I covered the soldered connections with hot glue to insulate them as I'm just leaving it floating around for now and I don't want it short circuiting anything

You can see the second keyboard connector just above the round coin cell battery in the bottom left of the board. You can see I've added some Kapton tape. I had to remove the original 5 pin connector as it wasn't providing good contact. The N-Go board is actually a pre used item, I think the original owner may have been a bit rough with that particular connector. Unfortunately I couldn't find a connector in my parts bin that was the right size, so I had to cut off the surplus pins and I wrapped the tape around it so when the keyboard connector is pushed in, it can't slide left or right inside the socket. Eventually I will replace this with the correct sized one, but it will do for now.

In this picture you can see I've added a Raspberry Pi 0 to the connection pins just left of the Expansion Port. This isn't really needed but since I have some Raspi0 boards doing nothing, I thought I would add it. This means that the Raspberry Pi0 can act as a "Accelerator" board adding a few extra new features, one of which is the ability to load ".TZX" files. These are perfect digital facsimiles of original Spectrum cassettes. When you load one up, the Raspberry Pi will simulate a real tape loading in realtime with all those nostalgic screeching noises.

On the far left, you can see in both pictures that I've extended out the switches running down the left side of the N-Go board. They aren't very neat, I've hot glued them in place and they all work fine. If ever I need to remove the board completely from the case, I will have to either desolder the switches or clip the wires and add some Dupont connectors to reconnect them, but for now they are fine. They look a little ugly I guess, but you won't see all that when it's fully assembled. So now I can reset the machine, select a drive or trigger the NMI (none maskable interrupt) menu, using switches on the side of the machine.

In the top right you can see a wire that runs across the board. This is just a wire that connects to a push latch switch that allows me to power on or off the system. Original Spectrums actually never had a power switch and this clone is no exception, however, the designer included a jumper near the power socket that allows you to connect a switch, or you can just attach a "jumper" which will keep the machine "switched on" permanently. That would be fine but it would mean having to disconnect the power to switch the machine off and that would wear out the power socket eventually. The cable to the switch is a longer than it needs to be as I hadn't figured out exactly where I was going to mount the switch. It's not doing any harm so I will probably leave it like that.

I've mostly just been using bits and pieces I have in my parts bin to do this so there's a lot of "eyeballing it" and improvisation going into this lol

Next I will show how I installed an SD Card extender so I don't have to access inside of the case to switch out the SD Card storage which contains the software and firmware that runs on the machine. Hopefully I will also get the built in cassette deck working with the N-Go board, oh and add sone external controller/joystick ports, then hopefully it will be essentially finished

 

[Outdated]

I don't have the knowledge to understand a lot of what you're doing but looking at those pictures is a bit of a nostalgia trip for me. The simplicity of the board by today's standards and the old plug fittings. And the ZX with a built in tape reader! I never had anything that fancy, I had an old TRS80 that I bought second hand off of a ham radio operator.

Most of the software I got with it was old time pirate copies - A4 photocopies of pages in books.

 

[MildredHubble]

I don't have the knowledge to understand a lot of what you're doing but looking at those pictures is a bit of a nostalgia trip for me. The simplicity of the board by today's standards and the old plug fittings. And the ZX with a built in tape reader! I never had anything that fancy, I had an old TRS80 that I bought second hand off of a ham radio operator.

Most of the software I got with it was old time pirate copies - A4 photocopies of pages in books.

"Through hole" components are wonderful to work with. There's quite a lot of surface mount components on the board but most of what I'm interacting with is nicely oldskool!

It will be nice to get that original cassette deck operational too. I like loading software from cassettes. I told my uncle a while ago that I was quite excited that I had picked up a brand new "Shoe Box" tape recorder so I could load tapes on my computers and he said "Mildred, I think you are quite mad..."

I also remember old "type ins"! I used to get photocopies of photocopies to type in that were so poor quality you could barely make out the print, but that was ok as you learned how to debug and take some educated guesses when it came to "O" or "0". Occasionally frustrating but in the end it was fun and educational!

I really like that technology has advanced to the point where it's feasible for hobbyists to design and manufacture new versions of the kind of machines you'd have to be a multimillion $ corporation to have made back in the 1980s in any kind of volume. It's also fun that these oldskool machines still have some relevance and can create some excitement decades after they became "obsolete"

 

[Outdated]

Maybe an interesting side note for you, I only bought a computer because I wanted to know how they work and I don't learn by listening to others, I have to learn by playing around and learning in my own way.

I got this knew computer and a whole herd of software but you have to type the code in manually before you can run it. Me having no knowledge of code at all back then it all looked like gobbledygook even though it was only basic.

So I couldn't read a section of code and then type it in, I had to type as I kept one finger on the hardcopy page of text that I was loading from. I had to type one handed and I'd never been taught to type either.

Turn the keyboard 90 degrees clockwise, now it's 4 fingers wide with your thumb for the space bar. That's how I learnt, using it like a big calculator. I ran a typing tutor program a few times to see how I was doing. One handed I was doing 35 words a minute with 100% accuracy.

Old habits never die but often they twist a bit. These days I type 2 handed but still mostly only using 2 or 3 fingers. It looks funny but I'm not too slow.

 

[MildredHubble]

Maybe an interesting side note for you, I only bought a computer because I wanted to know how they work and I don't learn by listening to others, I have to learn by playing around and learning in my own way.

I got this knew computer and a whole herd of software but you have to type the code in manually before you can run it. Me having no knowledge of code at all back then it all looked like gobbledygook even though it was only basic.

So I couldn't read a section of code and then type it in, I had to type as I kept one finger on the hardcopy page of text that I was loading from. I had to type one handed and I'd never been taught to type either.

Turn the keyboard 90 degrees clockwise, now it's 4 fingers wide with your thumb for the space bar. That's how I learnt, using it like a big calculator. I ran a typing tutor program a few time to see how I was doing. One handed I was doing 35 words a minute with 100% accuracy.

Old habits never die but often they twist a bit. These days I type 2 handed but still mostly only using 2 or 3 fingers. It looks funny but I'm not too slow.

That's so similar to the way I'd type in software! Either with my left hand tracking each character or word on a magazine page or photocopy and typing with my right! I got good at hitting the shift key with my little finger and stretching my index finger for lower or upper case.

Talking of skills "twisting" it turned out that I had built up muscle memory that was useful for playing piano/keyboard. It was like I had been playing chords with my left hand and melodies with my right hand the whole time!

The only problem I had back in the day was if I had shifted accidentally by one column of keys on the keyboard, I'd look at the monitor and realise I had transposed a significant amount of text slightly to the left or right. I remember looking at it and thinking "You know what would be handy? I programme that shifts everything back to the correct characters!" I don't think I ever ended up writing one that did that though.

 

[Outdated]

I still look at the keyboard as I type. These days it's mostly habit, sometimes I notice that I've been writing for a while without looking, my fingers do know where all the keys are. What really amazes me is how many typos I can make while actually watching where I put my fingers.

I never had a musical bone in my body. All of Mum's family played musical instruments. Mum had a piano accordion, she also played the piano and the banjo and she was good with the flute and the recorder. None of us kids took to music at all. In music lessons in Grade 2 they put me up the back of the class and I played the triangle, I couldn't play that in tune either. That was the end of my music career.

 

[MildredHubble]

I still look at the keyboard as I type. These days it's mostly habit, sometimes I notice that I've been writing for a while without looking, my fingers do know where all the keys are. What really amazes me is how many typos I can make while actually watching where I put my fingers.

I never had a musical bone in my body. All of Mum's family played musical instruments. Mum had a piano accordion, she also played the piano and the banjo and she was good with the flute and the recorder. None of us kids took to music at all. In music lessons in Grade 2 they put me up the back of the class and I played the triangle, I couldn't play that in tune either. That was the end of my music career.

I was also "that kid" that was given a triangle or a tambourine at school. It was very frustrating as I really very much wanted to learn how to play a "proper" instrument. It continued until I was in secondary school and my dad finally agreed to get me a guitar. Much like you did with learning how to code, I did with the guitar. I basically figured it out by trial and error, I really struggled to learn from other people "teaching" me.

I got pretty darned good at it in the end. I can play anything I want to, if I really want to. The problem is I've got barely any idea what notes or what key I'm playing in and that's been the case probably for two decades now lol! But my level of ability musically is quite advanced, I'd just be considered a dunce when it comes to music theory. I understand it in an instinctive way, but I'd really struggle to transcribe anything I play as written music!

So don't count yourself out if you ever feel like learning an instrument! Just do what you did when you figured computers out

 

[Outdated]

Remember those cheap plastic horns that were a fad for a while way back when? Voo voo something or other. Out of our group of mates I was the only one that was able to get a sound out of it, but I quickly discovered I could play it. Trouble was the only horn song I could think of was The Last Post and everyone told me to cut it out.

 

[MildredHubble]

Remember those cheap plastic horns that were a fad for a while way back when? Voo voo something or other. Out of our group of mates I was the only one that was able to get a sound out of it, but I quickly discovered I could play it. Trouble was the only horn song I could think of was The Last Post and everyone told me to cut it out.

I do remember those! I think they were popular around the time of some football/soccer event. Can't think for the life of me which one as I have absolutely no interest in sports lol!

I once got a hold of a Clarinet and after about half an hour I'd managed to play most of the Pink Panther theme tune. I was also told to "knock it off!" I do keep an eye out in thrift stores for clarinets but I haven't been lucky yet

 

[Outdated]

An old joke that might get deleted quick:

One morning a man woke up and went to the toilet for a wee, and it sprayed all over the place like a fountain. He took a closer look at his penis and there was multiple holes in it. He went to se the doctor about it.

The doctor used a wooden spatula to poke it around a bit and look at it from different angles while he ummed and ahhed a bit, then he wrote down a phone number on a bit of paper and said "Give this bloke a call.".

The man asked "Is he a specialist?" and the doctor replied "Sort of. He plays a clarinet so he can teach you how to hold it.".