Wednesday, September 01, 2021

Can you hear me, Mother?

 About three years ago I acquired a pair of Amstrad CPC464s. One I sold on to help pay for the initial outlay on the bundle (which also included my Plus/4) but I kept the other as it wasn't in the greatest condition and I had, to be honest, never owned a CPC before.

Clear the decks! It's huge!

As part of my escapades with the CPC, I added an audio in mod. This allows me to load games via the sound output of my phone - or anything else with a 3.5mm audio jack. Unfortunately, I'd found that it was quite unreliable and would not load a lot of the games I'd managed to find on the internet. I put this down to the software I was using to convert the .cdt format files to .wav format being a bit flaky and my phone not outputting the volume loudly enough. And so I put the CPC away for a long while; I even pinched its Z80 processor to assist in the diagnosing of a poorly ZX Spectrum +.


Oi! That Z80 is MINE!

Z80 restored and ready.

Fast forward a couple of years and there is a rather excellent YouTube channel called "Noel's Retro Lab". As the name suggests, a very nice guy called Noel repairs and explores retro computers and games systems. And as luck would have it, he dedicated a whole video to the exploration of modding the CPC with an audio in jack. See that HERE.

To cut a long story short, my original mod was incorrectly fitted. I had attached the inputs to the actual cassette read head. While this did work it did have a couple of disadvantages. First, it seemed to need the 'Play' button pressed to pick up the input. Second, as mentioned above, it wasn't very reliable. 

The NRL video is very detailed and well worth a look but, very simply, by moving the '+' side of the input to the correct side of capacitor C317 (the red wire), this meant that the input signal would pass through the op-amp circuitry of the CPC, giving a strong and stable signal at just the right location. And no need for the tape 'Play' button to be pressed.


New wiring - thick black
and red wires re-soldered

I also moved the black negative wire from the play head to a more generic 'ground' connection. It probably wouldn't have made any difference but not really worth taking the chance.

And now... how to be a complete freakin' moron.

As suggested, I also have a ZX Spectrum on my bench which I was originally going to try with my batch of cassette recorders. I had problems though (another post inbound on that) so I re-focussed on the CPC. 

But guess what happened. I had two power plugs on the bench. One was 5v max current of 3A with centre positive plug, the other was 9v max current 1.4A with centre negative plug. When I plugged in the power and switched the CPC on, nothing happened. Guess which one I had plugged in to the CPC? (I'll give you a clue - it was the wrong one.)


!


Oh. S**T.

Fortunately, my immediate incompetence was saved by past me making the competent decision to unplug the 9v 1.4A centre negative supply from the mains. Bullet well and truly dodged.

Anyway, with power now sorted it was time to see if the mod now worked. Since it was a long time ago that I last used the CPC I had long since lost the .wav files I had of the couple of Amstrad titles I'd found. My hard disk has also been changed out in my laptop for a nice shiny SSD following a hard disk failure too so I no longer have the software that converted the .cdt files to .wav. I finally managed to find an Android app called Tapdancer. This takes the .cdt file and plays it directly out of the headphone socket of my phone. It's quite old though, and is not on the Google Play store. As a result I can't really recommend it but it did work for my test purposes.

Next problem. Finding something to load. Eventually I found a .cdt of a Spanish motorcycle racing game. Google is your friend.  Tapdancer happily accepted it and converted it but, would it load? No. Not initially. The problem though was that the cable I have kept popping out of the headphone socket on my phone. I suspect it has 'had it'. A bit of fiddling later I managed to get it to stay in.

Would it work on the second attempt? Yes. Flawlessly.


Speccy photobomb

It works!

On the first load I realised the game was in Spanish with no English option. This was a problem when I re-defined the keys and ended up with the directions and acceleration all mixed up. Not the easiest game to play with keys like that.

Next up, WEC Le Mans. And it was the English version so I could at least get the keys re-defined correctly. 

I like all racing games. Even this one.

And, again, it just worked. After about five minutes the game started straight up with no complaints. The game itself seemed OK for the time i.e. it's no Gran Turismo. With only one apparent track and quite hard time limits it's quite difficult but the graphics are cute, especially when you crash and the controls are OK, if a bit slow. I'd give the game a solid 6.5/10. 

And that's basically it. The CPC now works quite happily with .cdt files playing directly from my Android phone. The only thing I have left to do is find that piece of software I originally had that converted .cdt to .wav in case I feel the need to try a direct player (instead of TapDancer).

The CPC is also proving to be the most solid and reliable machine I have. Nice.




Sunday, August 08, 2021

iMac G4 Shenanigans

We all tend to look back at events and things in the past with slightly rose tinted spectacles. I remember looking through my Grandad's old Cine films looking for 'the parrots' bit. This was where he had been on holiday in Majorca sometime in the early 80's and one of the locals had a parrot show where the parrots would do various funny things for the amusement of tourists. Growing up, I thought that this was the absolute best thing I had ever seen and it was a staple when visiting Nan and Grandad. Fast forward fourty years and I was sad to discover that that bit of footage was only about three minutes long and was, to be honest, a bit underwhelming.

And, after the excitement of getting the thing working, that pretty much describes my first experiences with the iMac G4. Underwhelming. (But that's not the whole story...)

I know that it's 19 years old. I understand that. I realise that technology has marched relentlessly forward; the web has changed, encryption and security have improved. I get all that but for some reason I was expecting more from a machine that at launch cost $1799 (almost $2600 in 2021 adjusting for inflation).

The Interwebs

So, anyway. First things first. What was the iMac G4 like to use on the modern internet? Well, if you read my previous post on this machine, you'll know that I actually managed to download quite a few things, and after a bit of work I managed to find a modern-ish browser that will load modern websites. 

First up, Twitter. Well, it works. I can't deny that. But you would need the patience of Job to be able to cope with using it. On a modern PC the twitter page updates itself every so often which is quick, seamless and unnoticed by most users. On the G4 it's slow, slow and then decides to slow down a bit. Typical time to render the home page is around 80-100 seconds. Every time it updates. Every time. Not really usable and only worth the novelty value.

Next up, Facebook. Well, this one refused to log me in. It got further than the ancient version of Safari but point blank refused to go past the login page. Oh dear.

Blogger. This one appeared to work but was, as twitter, excruciatingly slow. Then the version of Firefox I have on the iMac crashed. Ah.

At this point it was time to give up on any idea of using this for any type of web browsing. The 800Mhz processor just doesn't seem up to the job. 

Now what?

VNC

One thing that occurred to me is that, although this machine doesn't have the grunt for modern uses it doesn't need much grunt for the famous VNC Viewer. If I could find a VNC viewer that runs on this iMac then maybe I could use it to control another, more powerful machine that can be hidden away. Part of my issue is that both Mrs Crashed and I love the way the iMac looks and it's currently sat in our bedroom, just looking cool. But to be useful it really does need to be able to access the internet. No other machine is ever likely to be permitted in the halo'd confines of the bedroom, so don't even suggest it..

So, my ridiculous plan. Set up a headless Raspberry Pi with the desktop gui and VNC server enabled. Then, assuming VNC viewer is available for the iMac, connect via VNC and use the web browsing capabilities on that machine. It doesn't need to do much, just BBC News, Blogger, that sort of thing.

After a bit of Googling (or Safari'ing) I found that VNC viewer for PPC was available from here. Installation was simple and done in two minutes. After setting up my Raspberry Pi with VNC Server, it just worked. I managed to pull up the screen of the Pi and re-size the window so Chrome appeared as it would as if it were a browser window running native on the iMac. All in all, despite being a compromise, the results are quite good. No YouTube though.

Other Internet Options


The most excellent @ActionRetro1 on Twitter (and YouTube) has made a couple of websites that are designed specifically to run on very old, vintage computers. Although my iMac is possibly a bit more modern than was originally intended, the outcome is a very usable system. The websites are:

  • frogfind.com
  • 68k.news

68k.news


frogfind.com



As the names suggest, frogfind is a very lightweight search engine that uses DuckDuckGo as it's engine, and 68k.news aggregates news stories into simple text, meaning that viewing and reading is simple, fast and also ad-free. Both are really worth a look if you have an old machine on the intertubes and they prove that you can enjoy some online action if you don't fancy messing about with that VNC nonsense. They also work very well on modern machines if you're sick of all the ad-induced slow down. My iMac G4 displays both sites quickly and perfectly in the ancient version of Safari that is installed.


Games

Another reason for having this machine is to play games from the era. One such game that I have on PC and really do enjoy playing is Sim City 3000. This is one of the last decent versions of Sim City and is before the company that shall not be named got hold of it and screwed it into the ground. Having found the appropriate files to download I was a bit disappointed to see that the installation would not work as I did not seem to have the 'Classic' environment installed.

Dangnabbit.

After some research I discovered that the iMac PPC machines could run MacOS9 and earlier software in OSX but they needed parts of OS9 installed to be able to do so. In my installation I didn't have this, hence the failure to run the installer for Sim City 3000. When I got the iMac I did a fresh installation of OSX 10.4 which did not (or at least I can't remember it) give me any options to actually install or set up this functionality.

Below is the procedure for how I manged to install the Classic environment and make it work. I have recorded it here as it took me bloody ages to find it out and it needs a specific file to be downloaded from the Apple website. The link for that file is here but note that I can't guarantee it'll be there forever as it seems to be one of the very few bits of MacOS support that they haven't just binned from the website.

1) Download the file either directly onto the iMac desktop or copy it onto the desktop from a USB stick

2) The file is a .dmg file so mount it as you would any other disk image (on your Mac - duh!)

3) Head to the 'English' folder and look for the file called 'NetBoot.pkg'.

4) Right click (or ctrl+mouse button) and choose 'Show Package Contents' from the menu.

5) Go to the 'Contents' folder, then into 'Resources'. Find the file that is named 'NetBoot.pax.gz' and drag it onto the desktop.

6) Double click the file and extract the folder named 'NetBootInstallation'. If you get an 'Access Priveleges' error then you need to give yourself read/write permissions. Do this by right clicking (or ctrl-left click) and click 'Get Info'. In the window there's a section that says 'Ownership and Permissions'. Set it to 'read and write'.

7) Open the NetBootInstallation folder and find the file called NetBoot_HD.img and double click it to mount.

8) Find the 'System' folder and drag it to the iMac's hard disk.

9) Finally (phew!), go the 'System Preferences' and on the 'Classic' pane, click 'Start'. 

There should be some update messages, I certainly got a few, but after a minute or so the Classic environment should be running and voila! You should now be able to run Classic MacOS software. (Steps based on an original post from the Apple forums located here.)

Did it work for Sim City 3000?

Oh, yes. :)


Conclusion


The iMac G4 looks cool. It does some stuff OK but there are compromises. It's an OK retro machine but, even though it may still look modern, it is not so don't expect too much of it. With a bit of work it is an entertaining (and cool looking - did I mention that?) machine to use. If one comes along cheap, it's worth a shot.





Wednesday, August 04, 2021

Compact Cassette Cornucopia

 I got lucky on eBay again. Twice. First, I managed to bag a Philips D6310 cassette recorder for a fiver. This is a chunky cassette recorder that I'd intended to use with my Spectrum+ (see, there is a link to retro computers!). It was a bit bigger than I expected when it arrived but it looked cool and, initially, played cassettes fine, just needing a bit of a clean and a new belt.

But then disaster struck. One of the main drive cogs disintegrated. It was literally the consistency of chocolate and after playing 'We Didn't Start The Fire' a few times from Mr Joel, it gave up the ghost and chewed up the tape as a result. Fortunately, the tape survived. The cog did not.

To see what happened I took it apart (as you do) as the affected cog was buried deep inside, and ended up with a large bag of many, many pieces. This particular cassette recorder has its mechanism primarily constructed of plastic and is fully auto-stop on all functions. As a result, once I had it apart, I wasn't convinced I'd get it back together again - not that it mattered as I would never get a replacement cog in any case.

So, second stroke of luck on eBay. I saw a job lot of five cassette recorders on eBay and managed to bag the lot for £5.50. Bargain. The machine I'd specifically been looking at was the WHSmith unit. But I'm getting a bit ahead of myself.


BARGAIN!

By the time the magical box of five cassette recorders arrived, I had found that someone had a 3D print available on Thingyverse of the offending cog from my D6310. (Interestingly, the same cog was used for many Philips cassette recorders.) And who should have a 3D printer to hand? My illustrious brother. After a few days a pack of six resin printed cogs arrived. Two were immediately rejected as some teeth had broken off. But that left four candidates that could potentially bring the D6310 back to life.

By this point, and much to Mrs Crasheds amusement (she was not amused), I had six cassette recorders in need of various things. They were:

Philips D6310

  • New belt needed
  • Drive cog stripped
  • Needs a clean
  • In a million pieces - put it back together!

A ) WHSmith CPD8300

  • New belt needed
  • Buttons Broken
  • Runs very sloooow

B) Sanyo DR-101

  • New belt needed
  • Needs a clean

C) Sanyo M-787AG

  • New belt needed
  • Mechanism VERY noisy
  • Fuse blew during testing

D) Bush (Rank)

  • New belt needed
  • Needs a clean

E) York Radio Cassette

  • No sound
  • New belt needed
  • Really needs a clean

A to E as above


I shall cover the other machines in another post but, first things first. Let's get the D6310 back together..

A small cog in a large machine

An appropriate cog was selected to replace the chocolate one. As the picture shows, the original really is shot to pieces. Next, I laid out all the pieces to understand the scale of the problem I'll be facing...


Your leg bone's connected to your ankle bone..

Getting the transport mechanism together was not as difficult as I had originally expected. I had, by some good luck, managed to find the D6310 service manual and there is also a fantastic website with some good quality photos of a unit that I could also refer to. The new cog can be seen on the right side next to the capstan in the pic below..


Piecing it all together...

After an hour or so I had the transport mechanism back together. As it turns out, the only mistake I made was the auto-stop lever ended up on the wrong side of another levery thing so it went clunk clunk clunk instead of just click. This excellent website helped me out here too, with me realising my mistake eventually while reviewing the photos available.

A few points:
That spring at the front of the mechanism was a real pain to get in correctly. It's really strong and has to sit at the bottom of the post it sits on or everything will just not fit and then spring off into the carpet.
The mechanism is all plastic but is surprisingly robust.
I forgot to re-install the Pause button bar and had to remove the buttons and do it all again (including that bloody spring).


Back together
Now with added Pause bar!


Finished!

After I managed to get everything back together it was time to test it. I was concerned that the cogs that had been 3D printed might not be up to the task. But these were resin printed and, so far, the one I selected has not broken. The player is quite noisy though which I suspect is because that cog is much harder than the original. It could be that the material of the original was specifically selected to reduce noise. But it works!

Now I just need to find the time for the other five, and that's before I test them on a Speccy!


Tuesday, July 27, 2021

There's a Storm a Brewin'

A short post this time. If you're into your Amiga stuff then you'll almost certainly have heard about the PiStorm. This amazing little board, in conjunction with a Raspberry Pi 3A, adds an inexpensive (but see below) accelerator to a stock A500 with the possibility of large amounts of RAM, SCSI hard disk support and retargetable graphics too. All for what should be the cost of about £11 plus a Raspberry Pi 3A (currently £23.40ish).

BUT

Chipmageddon is upon us. There is a worldwide shortage of silicon at the moment and it's affecting every industry from toasters to luxury cars. Even us hobbyists are not immune. The key component of the PiStorm is a small CPLD (think a tiny re-programmable chip like an EPROM), which holds the firmware and does the heavy lifting. They should cost a couple of quid, but with extensive supply problems, prices have increased dramatically. There are some stocks out there but they're not cheap.

So, until chip supplies stabilise - which could be Q4 2022(!) - expect to pay anywhere from £30 to £50 for an assembled PiStorm (without a Pi 3A).

Before I go any further I should also point out that the software behind the PiStorm is still very much 'Beta'. If you want a fast accelerator that is 100% compatible with all games etc then this is not the product for you (go and get a TerribleFire or something similar if that's what you're after). But updates are regular and huge progress is being made with every update.


PiStorm in place of MC68000

Pi 3A mounted on the PiStorm


The PiStorm board replaces the 68000 CPU and the Pi 3A plugs into the board. Setup is surprisingly straightforward if you just want a basic accelerator. I managed to get the rough equivalent of a 40Mhz 68030 with three SCSI drives (image taken from my existing 4Gb CF card) and 128Mb of fast RAM with the minimum of effort. Things like RTG and networking require a bit more effort and I plan to get these going on my board when I have time.


Look at the size of that.....memory!

The only issue I found was that the board I had kept popping out of the 68000 socket. Given that I intend to keep this board and just update it as and when it has updates I decided to take the slightly drastic step of soldering it directly to the motherboard. It would be relatively easy to remove if needed but ensures that no more popping out crashes occur...


Now get out of that!

A happy consequence of doing this is that my RGB2HDMI now has clearance to connect a HDMI cable. Yay! 


Let's all just get along.

At this point there are still several things I want to do, as mentioned above:

1) RTG support - "...colours! So many colours!..."

2) Networking - not sure if I could tweet from my Amiga but it would be cool if I could...

3) File copying between Pi and Amiga - useful for new apps or updates to apps

4) Investigate if the Pi can be controlled from the Amiga over SSH?


And at least I've found a use for two of my Raspberry Pi! Stay tuned for more.

Friday, April 30, 2021

Baby Beeb

I received an unexpected message from one of my work colleagues over a weekend. 

"Would Mrs Crashed allow this in the house?"


The Offering


Well, my immediate response was a resounding "Yes!". Better to seek forgiveness than ask permission. :)

There have been many hundreds of words and hours of video produced about the BBC Micro and Acorn Electron. Here are a few links to some of them:

MICRO MEN - (search for this one yourself)
Nostalgia Nerd - The Electron Story

Suffice it to say that the Electron is a cost reduced BBC Micro which, at the time, dominated the UK educational market. The Electron was intended to fight against the cheap and hugely popular ZX Spectrum while trying to capture some of the lucrative games market. It was not a success largely down to its late arrival because of ULA issues. 

My own experience of the Acorn products is, to be honest, a bit thin. My school had a computer (one computer) that was a BBC Micro model B. It was tucked into a cupboard with enough room to fit two kids on tiny wooden chairs. Time was strictly limited and the software provided was somewhat rudimentary. One application I remember asked questions and we input answers and some of my 9 year old compadres spent the lesson teaching it rude words and offensive names (suspiciously prescient of the Microsoft AI debacle). I spent probably less than 1 hour in total on the thing in the whole time I was at the school.

Anyway, a box from my most awesome work colleague duly arrived containing the previously pictured Acorn electron. 


Unboxed and ready for inspection.


First things first, does it work? Now for certain other computers there are extensive lists and descriptions of what tests you should do, what components to check etc before you even think about the merest possibility of considering the outside chance of plugging it in. In this case, nah. The power input is 19vac. Fortunately, I managed to get a 'real' Electron supply from the most awesome and all round good egg @GeezerD205 on Twitter.


Hmm, re-worked end..


Connections to be re-worked...

The power supply is as simple as it could be. A transformer. That's it. Input 230vac, output 19vac. I did a little re-work on the connections inside but failed to take a picture of the results. Suffice to say, I'm happier with my results that the insulating tape that originally covered the wires, and a measure of the output confirmed the expected 19vac (or near enough as there was no load on it when I tested).

Time to plug it in. Does it boot? Yes. A nice satisfying beep, and the composite output sprang into life.


Yay! It boots, and the keyboard works!

I did a quick keyboard test and everything just worked. Nice.

But wait a minute, where's the 'M'? 

Well, that's annoying. Just one key not working. Fortunately, the keys on the Electron use switches and not the dreaded 'membrane'. The switches are actually the same as on the BBC Master and can be dismantled, cleaned and re-assembled. In theory. Something to sort out when I can get out into the garage..

Next, it really needs a bit of a clean. It's not as bad as some of the machines that have crossed my path, but it definitely needs a bit of a spruce up. Time to get the screwdriver out and strip this thing down...


I'm in pieces, bits and pieces.


Grubby Keyboard


Baldwin supervises the initial clean-up


Keycaps - nice and easy to remove


The keycaps were very simple to remove and firmly attached, but not 'break the keystem' tight like they are on my Plus/4. A simple wash in soapy water was all that was needed to get the keycaps clean and then a leave to stand for a few hours to air dry.

While the keyboard was disconnected it was time to have a look at that dodgy 'M' key. The key switches need to be de-soldered from the keyboard circuit board which was fairly simple. Then, in a fit of sensible thinking I de-soldered the right shift key switch and put it in the spot where the 'M' key was. My thinking was that if the right shift key doesn't end up working I can use the left one. 


Back of the keyboard - 'M' key circled

'M' Key removed..


Anyway, I brute-forced the keyswitch open which was a mistake. In actual fact, the two legs that are soldered to the board actually unscrew and allow the two halves of the switch to separate. Inside are the two metal contacts that are pressed together when the key is pressed. 

I cleaned both metal contacts in the switch and carefully re-assembled it. Fortunately, despite my heavy handedness, it screwed back together OK and, even though two of the three plastic clips had broken, the switch unit held together and was simple to solder back into place. 

Initially, the switch didn't appear to work. If I pressed the right shift key it made no difference but then, after a couple of presses, it suddenly started to work. Presumably, by pressing the key a few times, the spring contacts inside re-seated correctly and began to make contact again. Nice. 

And finally, the case was washed in soapy water and left to dry before re-assembly. The results are quite nice. There's no yellowing and it looks almost fresh out of the box.


Shiny. Shiny.

I don't have a simple way of loading any games or other programs at the minute. I'll probably end up getting something but for now I need to get a compatible cassette recorder and the correct cable.

In the meantime, would you believe that the 'P' key has started to act up now. Oh, well. At least I know how to get the key switches apart now. 

Time for some gratuitous motherboard shots:


Mother. Board.

Hmmm, resistors...

Logic chips.

Memory!

I've got the power.

The infamous ULA with early low insertion force socket.

More on the Electron soon. 


Tuesday, February 16, 2021

A Change of Plan

So, I'd been waiting for ages to get some time to sort out a Pi Zero version of the excellent Pi1541 which now supports the Pi Zero (surprise, surprise). I'd got as far as making a nice cable, I had the level converters, I wired it up and even installed the software. All I needed was a suitable Commodore machine to try it on and the only one I have is my trusty Plus/4.

Finally, I got the Plus/4 out of storage, plugged it in and... it didn't work.

To cut a long story short it looks like the PLA has died. So this project is on the backburner pending the arrival of a new, working PLA.

Now what?

Well, I had noticed the ripples in the Amiga universe regarding a somewhat unbelievable sounding project that would give proper, lag free HDMI output on an Amiga A500, all for the price of a small adapter board and a Raspberry Pi Zero.

Interesting.

Of course, I had to get one of these being a bit of an Amiga nut (it says so in the tiny bio over there ->). The gerber files for the adapter boards are freely available so I could have just used one of the many PCB prototyping services to generate a small run of brand new boards but I didn't want the hassle. As I am no longer what you would call 'young' I also didn't want the hassle of trying to solder the small number of SMD components on to the board that make the magic happen. 

In this case, eBay came to the rescue as I found someone who already had some adapter boards, with SMD components already installed and all for a very reasonable price. I won't put any links here as it's eBay and you can search it out for yourself. So there.


SMD - Too small for my ancient
sausage fingers.


Look at the backside on that.


The only things missing from the board I received (very quickly - nice one) was the pin headers, a chip socket and the 40 pin socket to accept the Pi Zero. I already had a chip socket and a 40pin socket header so I just needed pin headers. And eBay came to the rescue again. Yay!

Finally, I already had a Pi Zero which was originally intended to be the Pi1541. No longer.

Quick summary - this board fits into the Denise socket and the Denise chip fits into the adapter board. The Pi Zero fits into the 40 pin socket. Plug in a HDMI cable. Bob's your Uncle (well, he's my Dad actually).


All present and correct.

Building the board was a bit more of a journey that you'd think so I shall try to put everything here in order so that you don't have to struggle if you do one of these. It's worth noting that there are plenty of videos of people building these things on youtube, including the excellent Jan Beta who had similar issues to me.

So, first, solder in the Denise/Super Denise headers. This should be a header with three pins and, as I found out, it should be right angled. The one I put in was actually straight and I didn't realise that this was an error until later. If they are straight, they stick up (down?) too far and will stop you inserting the completed unit into the chip socket on the A500 motherboard. I didn't have any right angled headers so I had to use a frightening amount of force to bend the straight pins I had install to 90 degrees. Not a fun 30 seconds and not recommended. If you are only using this on a machine with standard Denise or only with a Super Denise you could obviously just short the correct holes together instead of fitting header pins.

Second, solder in the pin headers. These are the pins that will fit into the Denise socket so I made sure to get the narrow, turned pin versions that are less likely to knacker the socket on the motherboard. Make sure you solder them in the right side. The 'soldering' side is the same as the side where the SMD components are with the long pins on the other side. To get them straight I actually inserted the pins with the board into a 48 pin socket so the whole thing was held firm while soldering. This worked quite well but was a bit nerve racking to remove it once I'd finished the solder work. Perhaps I should have used a bread board..


Headers soldered using a
socket as a guide

Next, solder the chip socket on to the adapter board, which is where Denise will eventually sit. This goes on the opposite side to pin headers so you're soldering the legs on the opposite side to where you soldered the pin headers. Make sure you line up the notch in the socket with the notch on the silkscreen on the board. 

Now this is where I had a little wobble because the solder joints from the pin headers actually foul one side of the socket, leaving it a bit skew whiff. To make sure this wouldn't cause any problems later, I carefully raised the other side of the socket so that it sat on the board as level as I could get it, even though this left it standing slightly proud and didn't leave much of the legs sticking through the holes. My socket was a cheap one. Other, higher quality ones might not have this same problem.

Now, solder the 40 pin socket on. Nothing controversial here. Just try to get it on flush to the board and straight. 

Jumpers, Headers and Socket
soldered in.


And from the other side.
Looking good.


There is an additional place on the board for another two pin header which will accept a switch. This is, apparently, intended to force resolutions in certain circumstances but is optional. I left it out.

So, in summary the order of soldering on the adapter board should be:

  1. Denise jumper (right angled!)
  2. Header pins (the ones that'll go into Denise' socket on the motherboard)
  3. Chip socket (for Denise)
  4. 40 pin header socket (for Pi Zero)

And that's it for soldering. Now all I had to do was plug it in and test it.

Installation is very simple. First, the software needs to be put on to the Pi SD card. I freshly formatted the 8Gb card that I had intended to use for the Pi1541. This is massively over the top as the actual software is a few megabytes as it 'bare metal' i.e. no operating system, just the necessary software to do what's needed. This can be grabbed from here. Just grab the latest release and copy the contents of the zip file to the SD card. That's all you need to do.

Next. Find an A500 and get it's top off. (Mine is just a bare A500+ motherboard I use for testing.)


Oh, Mother(board).


Then, find Denise and gently remove her from the socket and put her to one side.

At this point I pushed the Pi into the 40 pin socket on the adapter board. 


Top view (no Denise yet)

Bottom view.

Take Denise and gently press her into the socket installed on the adapter board. 

Then, finally push the whole assembly carefully into the now empty socket for Denise on the motherboard. It should now look something like this:

Installed - Wide(ish) Angle

Close Up.

From the side.

Right. Denise is in place. We are now ready to test. Fetch me your finest HDMI cable! 


Standby for action.

Does it work.....?  Of course. ;)


DMA Design. What could this be?

Oh, yes! More Lemmings.

Title Screen.

Level 1 Lemmings.

This board is AWESOME. If you have an Amiga A500 you HAVE to get this board. It should be a crime to use an A500 without this board. It is just amazing, the pin sharp quality of the picture. These photos just don't do it justice. And for the sake of a simple board and a Pi Zero. WAY cheaper than loads of the current solutions out there. Unbelievable. Just freakin' amazing. 

Get one of these for every Amiga A500 you have. What are you waiting for??

But, wait a minute....

Although this version of the board allows you to select either Denise (OCS) or Super Denise (ECS), it still only supports the OCS screenmodes. But for most users playing games this should not be an issue.

And another thing. I had hoped to show this working on that stupidly huge Sony 40 inch TV that lurks in my workspace, threatening to make my desk collapse with its weight. But it doesn't work. When the screen from the Pi initialises it selects a bizarre resolution that results in a squashed picture with glitches across the screen. I suspect that the TV is sending something odd down the HDMI cable and confusing the Pi. The TV is very old even though it is HD. As a result I will need to test on a few other TVs.

But why haven't you got one for you A500 yet? Go on. Get to it. Go. NOW.


Naked Amiga - A thing of beauty.