When I first started building my mini pinball cabinet, it was designed to be powered by the Steamdeck. This was mainly because I didn’t have a spare PC kicking around that could do the job.
The Steamdeck has being doing the job, but it had one issue, the loading times! Because the pinball software runs on Windows, I was booting Windows on the Steamdeck from Micro SD. Yes, I could have installed Windows on the Internal storage, but I didn’t want to mess around with dual booting and I wanted to actually use the steam deck for its intended purpose with Steam OS.
I decided I needed a dedicated machine to run the cab moving forwards, but I didn’t want something that was going to take up a load of space. So after looking around at various Mini PCs I decided to give the AceMagician AMR5 a go. This little PC runs an AMD 5800U processor with integrated GPU which I figured should do the job for my little 1080p cabinet. It also has a 512gb SSD and 16gb of RAM.
The PC has a USB-C port on the front so the cable that used to plug into the Steamdeck now just plugs into this. After running the Baller Installer and doing a few extra tweaks, my cabinet was back up and running, but now with amazing boot/load times.
All I need to do now is finish off the physical appearance of the cabinet and then setup some additional tables to play on.
After a trip down to the South West Amiga Group’s latest meet on Saturday, I strangely enough ended up returning home with an Acorn Archimedes A3010. The computer was labelled as non-working and I paid the sum of £50 for the privilege of bringing it home with me.
These computers are notorious for being destroyed by their onboard batteries. Thankfully the previous owner had already cut the battery out and cleaned the board, but then didn’t get any further with the repair.
I don’t class myself as an Acorn expert by any means, but I have done a lot of reading up on the Acorn machines in the past from when I repaired my RISC PC. From my previous repair, I also have an Acorn “POST Box” which is a little USB board that connects to the diagnostic port on 32bit Acorns and gets some extra diagnostic details from the machine.
Upon connecting up the board, I could see a RAM error message with the code 0000FFFF. These error messages are actually in Hexadecimal and therefore translated as 00000000000000001111111111111111 in binary. Indicating that the highest 16 bits of RAM were fine, but the lowest 16 bits were not working. The A3010 has two RAM chips on board and the one furthest to the right is responsible for the low bits.
After grabbing my multimeter and the schematics for the board, I probed all the pins and found the RAS line was not connected (RAS and CAS are used for selecting the Row and Column of memory to be read) and neither were 6 other pins. So my first repair was re-linking these traces. Some I just soldered on top of the board and some I used fine wire from the memory chip to the vias on the bottom of the board.
After this, I had a booting computer but quickly noticed the mouse wasn’t working. Using my oscilloscope I probed the LS241 buffer chip on the board that deals with the mouse signals. All signals looked fine going into the input pins on the chip apart from one bad trace, but there were no output signals at all. Luckily I have a spare donor board for the RISC PC which uses the same chip, so a quick transplant and another wire repair got the mouse back up and running.
Almost there, but one last problem was that the floppy disk drive not working correctly, it would initialise but then return an error saying “Drive Empty”. After doing a bit more research I found that the A3010 used pin 34 on the floppy to determine if there is a disk in the drive. I probed all of the pins and they all had connectivity to the controller chip. But most of the floppy control pins are pulled high to 5v via a resistor. I checked pin 34 and the signal was permanently low.
Further inspection revealed that the trace going to the pull-up resistor was broken. The same issue was affecting the index pin also (Pin 8). With both of these now repaired, the floppy drive came to life and I now have a fully working Archimedes.
Gotta say I’m pretty happy with how that repair went. And what better way to celebrate, than a quick game of Lemmings!
One of the most obvious Amigas missing from my collection was the Amiga A1200. I already have a CD32 with a TF330 card so this was my alternative to the A1200, but I decided that I needed to get the real experience.
So here it is, a lovely condition A1200 with 4MB of additional memory in the trapdoor and a compact flash card adapter mounted on the back to replace the 20 MB HDD that was fitted.
I have also moved my PCMCIA Network adapter to this machine and hooked it up to an ethernet to Wi-Fi adapter to connect it to my home network for internet access and transferring files.
Apart from a few creature comforts, I am keeping this one close to original including the floppy drive so I can load that original Amiga software.
I’ve been fairly busy recently and even though I’ve still been doing a lot of stuff with retro hardware, I’ve not found time to update this site. So I need to catch up, starting with this one which I have actually had for over a year but I knew it wasn’t working so has been sat in my pile of things to fix.
This is the Acorn Risc PC600. As with nearly all of these units, it came into my hands with battery damage. The leak was pretty bad, so the first step was to cut the battery off and clean it all up.
I then purchased an Acorn POST box interface which would allow me to easily read the power on self-test error messages on startup. Upon powering it on it showed that the CMOS was unreadable and it had sirq and virq errors (Sound and Video). Reading up on these it is usually caused by the buffer chip and the resistor network chip next to the battery, no longer being connected to the vidc chip. Using a multimeter I jotted down all the broken traces and re-joined them all.
Powering it back on whilst holding delete to reset the CMOS settings, the POST still gave a virq error and I was about to turn it off when it booted into RISC OS. At this moment in time I was pretty happy. There was still an issue but I had a functioning machine. I was able to test the HDD and the floppy both of which worked. It was then time to go back to my day job for a while, so left it there ready for me to come back later.
After work that day I went back into my workshop and the first thing I wanted to do was format a floppy disk. So I grabbed the mouse, clicked on the floppy drive and the screen went black. Powering it off and back on gave me nothing, and even POST wasn’t working now. After a few choice words were spoken, I started looking around and checking signals with the multimeter. It looked like the PC was being held in reset. These RISC PCs do something a bit unique when they are in reset where they do a count sequence on the address bus, therefore on a multimeter you see it where A0 will have a square wave at a certain frequency, then A1 will be half that frequency, A2, half again and so on. But I checked the reset signal and it looked like every other reset signal I had seen on 8-bit machines, goes high, then after around half a second, goes low.
Some head scratching followed, I expect some more swear words, then I read an Acorn technical manual that gave me the answer. The reset pin on these machines is actually active low! So the circuit was functioning, but the final output was the inverse of what it should have been. Checking the circuit diagram there was a not gate IC on the reset circuit that dealt with inverting the reset signal for the CPU. I ordered a new one and replaced it with the hope I would be back up and running again.
Well, this hope was soon dashed when I powered it back on. The system would POST now, so I had fixed that issue, but I still got the vidq error, followed by a red screen, and then at that point I lost all video output. So something was still wrong.
I spent quite some time going over every signal I could think of and they all looked ok, but by ok, I mean that the signals were there and doing something. What I didn’t know is if the signals were doing what they were meant to be doing. At this point, I decided to look at some other ways of getting this machine back running again.
I was fairly happy with the fact that all other components were working and there was just a board fault somewhere. So I managed to grab another Spares or Repairs board off eBay. This one looked in much better condition than mine so I was hopeful it would be an easier fix. When I got the new board I was again greeted with virq errors and also a DRAM error. I started going through each of the data bus pins to check that there were signals going to the vidc chip. I then noticed that two of the data bus signals seemed to be competing with each other and looked messed up. Confirmation of this issue was discovered when the helpful people over on the stardot forum explained that the DRAM error was actually a hex number and by translating that into binary it showed an issue with data lines 25 and 26.
Using a multimeter, I then discovered that D25 and D26 actually showed continuity between the two pins. The problem here is the data bus goes all over the motherboard so where was the short? I started easy and removed the ROM chips and the CPU, same issue. I then removed the buffer chips as these can go faulty, still the same issue. With only a couple of options left, one being the IOMD chip which was going to be practically impossible to replace, I removed the last easy component, one of the resistor network chips, at this point the short vanished! So I soldered everything else back in place, transplanted this IC from my other board, and finally a working RISC PC 600!
I am fairly happy with my repair as I do now have a functioning PC. But I think I am still going to have to go back and visit my other board. Now I have a functioning device I can see exactly what good signals should look like and can hopefully pinpoint the issue. I am fairly sure it’s going to be the data bus connection to the vidc chip, but the signals were all present, so now I need to look for ones that even though they are present, just don’t look like they are supposed to. I will post an update if I ever get to the bottom of the issue.
My next step is to start discovering what these machines are capable of. I have already swapped the drive out with am IDE to SD adapter and I think I would like to experiment with sticking a second processor in the unit. There is a board that allows a 486 processor to be inserted as a second CPU and then run DOS programs within a window in RISC OS, This sounds pretty neat and I do have a spare Blue Lightning 486 DX2-66 processor sat here wanting to be used.
Thanks go to Ian on the stardot forums for providing help through this repair and also building the Acorm POST box which proved very helpful.
The Dragon 32 was an 8-bit computer based around the Motorola MC6809E CPU which meant it was very similar to the Tandy TRS80 CoCo range of computers.
This particular example came to my collection as a nonworking example. When powered on the screen just showed a load of garbage. After dealing with a couple of other computers with this chip layout, I knew that the video chip works independently of the CPU, so the fact it was displaying garbage on the screen, likely meant that the CPU was not running the correct code.
A first check over with an oscilloscope showed that all the data and address bus lines seemed to be active, indicating that the CPU was at least attempting to run something. When a Dragon is first turned on it will perform a CPU reset and then start executing the ROM code from address $8000. I checked the reset line on the CPU which was functioning as expected (Low then High).
Maybe the ROM was faulty? This Dragon has two ROM chips, one lower and one upper, each 8k in size. The lower ROM chip contains the code to clear the screen, so if that chip wasn’t working then we would see the garbled screen. But also the upper ROM chip contains the reset vector for the CPU (It is this that specifies where to start running the ROM code from). So if either of these chips were dead, we would have an issue.
The ROM chips in this machine are 2364 EPROMS. Unfortunately, these can’t be read by the TL866 programmer I have, so I had to build an adapter to make it read as an M27C128 chip. But once I had done that, I verified the contents of the two ROM chips and they both came back fine, so not our issue here.
Computers that use the MC6809 CPU also tend to use another chip named the SAM chip. This chip does the address logic. So if this chip was bad, then when the CPU tried to read the ROMs, it might not actually be succeeding. I went over the pins on the chip and couldn’t see any obvious fault here either. Luckily my TRS80 CoCo2 computer uses the same SAM chip and it was socketed, so just to rule this one out I swapped them over and confirmed that this chip was fine.
If the RAM is faulty, then any instructions that the CPU stores data in memory won’t work. So once again this could cause the computer not to start up. But I checked all the CAS and RAS signals, along with the address pins and the data in and out pins, and I couldn’t see any obvious issues.
I decided then to dig out the datasheet for the CPU and started going over each pin to see if they looked like they were performing their duty. It was at this stage that I noticed the Read/Write pin on the CPU was stuck high and was never changing its value. Without this pin changing, the CPU will always be reading from the data bus but never writing to it. There is no way it can initialise the video chip without writing to the data bus. Unfortunately, the CPU in my TRS80 CoCo2 was soldered into place and I didn’t fancy removing that so I had to wait for a new CPU to arrive off eBay.
Once the new CPU arrived I swapped it out and powered up the Dragon, this time to be treated with the Microsoft Basic boot screen! A fully working Dragon 32 is now in my collection.
I have also discovered that my CoCoSDC adapter also works with this machine so I have an easy way of loading up some Dragon games from SD Card.
After playing around with the Video Genie system which was a clone of the original TRS80, I decided it would be fun to explore the Tandy line of computers a bit more. So after looking around a bit I settled on the TRS-80 CoCo 2 (Color Computer 2).
This particular example had the benefit of coming with the CoCoSDC which allows you to load the entire TRS80 software inventory from an SD Card. It even has a nice menu system to make the loading process nice and simple.
I’ve always wanted to try on the game Dungeons of Daggorath which is part of the storyline for Ready Player One (The book version).
This one is something a bit different. The Video Genie EG3003 is a hong kong made clone of the Tandy TRS-80 computer. It was sold under several different names worldwide such as the TRZ-80 and the Dick Smith System 80. But for us UK folk it was the Video Genie.
Although it was a clone of the TRS-80, it did have a few differences which meant that compatibility wasn’t 100%. The Video Genie also went through a few hardware revisions to make it more compatible. But the version I have was the original version 1 machine, which was known for not loading cassettes very reliably from the internal tape drive, and also missing some fairly vital keys from the keyboard!
This computer had apparently been stored in the upstairs room of a 2nd hand shop until someone asked them if they had any old computers, they dug this thing out and it changed hands a couple of times before it found its way to me.
This has been an enjoyable project for me as the system had a few different faults going on so gave me the chance to do some diagnostics and repairs. I will be doing a full write-up on what went on shortly so be sure to subscribe to my newsletter if you are interested in that.
For now, I will finish with a photo of the machine as I received it. It’s a big computer!
With the exception of an original Apple iPad and an iPod Nano back in the day, I’ve never owned another Apple device. On the mobile side, I’ve always had Android devices from their first release, and from the computing side, I’ve always been in the PC camp.
But back in the time of the 8-bit computers, I don’t think I was even aware of Apple. Living in the UK, I was brought up with names such as Sinclair, Commodore, Acorn and Amstrad. But on the other side of the pond, Apples seemed to account for a vast number of people’s first home computers.
Well, I figured it was about time I found out what all the fuss was about and recently came across an Apple IIc up for sale. It had the Wdrive SD card floppy emulator with it, and I’ve also built up an RGBtoHDMI board for it and purchased a joystick port adapter to allow me to use PC gamepads with the computer.
I am currently running a Hard Drive image on the Wdrive named Total Replay, which has a large selection of the best Apple II games installed with a nice GUI to control it all. It even has a nice “attract” mode which scrolls through some of the games if you leave it sitting there doing nothing.
Going to spend some time now looking around the system and seeing how it all works. Getting used to such oddities as the Delete key not actually being a delete key and instead just printing a weird square character. Apparently, this is a real thing!
I was given this old PC the other day along with a bunch of other bits and pieces that I am still going through. But this was definitely the most interesting item so I wanted to take a look at it as soon as possible.
After measuring the voltages coming from the power supply it was clearly dead, all voltages shoeing around 1.7Volts. A full re-cap had the potential of bringing it back to life, but these old power supplies were not that great. The huge fan on it also failed and rattled around as it tried to spin.
My decision was to buy a small ATX power supply and retrofit it to the unit. After slicing the connectors onto the modern ATX PSU, I measured all the voltages again and then powered it up.
And it is now booting! This one was actually fitted with an ancient Western Digital Hard Drive which has also died, it spins up and tries to read, but it doesn’t sound healthy and wouldn’t boot. The floppy drives, however, do work, and among the other stuff I picked up, was a set of 5 1/4 inch floppies including a Microsoft DOS Boot floppy.
The most interesting thing about this unit is someone has fitted an Orchid Tiny Turbo 286 processor board to it. I’ve not been able to fully test that yet as I need to build up an AT-XT Keyboard adapter. But the PC does boot with the switch in both positions so I think it’s fine.
The next steps are to fit a modern Hard Drive solution like an XT-IDE board, give it some sound with a modern Adlib Sound card replacement and then design and 3D print a bracket to hold the new PSU in place and mount the power input and power switch on the back of the unit. Should be a fun project!
Having had the NC100 whilst I was at school and having one again in my collection now, I have still always wanted its bigger brother the NC200. The bigger screen, built-in backlight, and a 3.5″ floppy drive made it a far more advanced device.
I’ve been keeping an eye out for a while now for a decent priced one, and finally picked one up for a price I was happy with.
Since this has a built-in serial port and terminal emulator, My next thing to do is to get this connected up to some old skool BBSs.
