retro computer kit

THE µKENBAK-1

Back again with another retro computer kit from the same creator as THE ALTAIR-DUINO, a small quick kit in the µKENBAK-1. The µKENBAK-1 with the µ in front denotes one of the earlier versions of the kit. This is smaller than the original computer kit, compared to the full-sized replica or nanoKENBAK-1 now offered by the creator. This is a small, and simple kit. Running off an Atmel processor (same as Arduino), this little recreation offers a fun, simple front panel, and relatively quick assembly.

Compared to some of the other kits that have been posted here, this one is straight forward to put together. While you have the classic soldering, the kit is all through hole components and is a pleasant hour or so to put together. The most time for me in putting the kit together actually came down to getting the PCB with the stand-offs in the case and lined up with the back holes. This proved to be a difficult, and time-consuming process. You need to pre tighten them on the front panel, which then slides into the case, and line them up with the back holes. Between the standoffs being plastic and wanting to strip, and them wanting to wiggle all over, most of my time went into this instead of soldering. In the end, I got 5/6 in place and called it a day.

The creator of this kit shows his experience in creating these kits, in little details, which make the kit a nice experience; one example is the usb extension cable which gives you an easy connection out the back is the perfect length to do the job but not be in your way. Another is the instruction booklet coming with a bunch of examples on how to use the computer, right after the assembly instructions. These instructions come in a nice spiral book included in the box.

The creators website, https://adwaterandstir.com/kenbak/ also goes into detail about the creator of this machine, (the original one in the 1970’s), and its history.

This is one of the easier kits I have done, but enjoyable in its ease to put together. I would recommend this kit to someone who is looking to get started with these kits.

Kenbak-1

Briel Computers Replica 1 Plus

Kit

I recently ordered the Briel Computers Replica I Plus, a Apple I clone. Instead of the originals big board to do a lot of NTSC generation, it uses a more modern single chip. The shipment came in a small box, and with everything I needed. The creator of the kit did a great job including everything you need, down to including an anti-static strap! The project came with some solder, but not nearly enough for everything, I think it was thicker to go with the structural points. Briel Computers sells the kit through ReActiveMicro.com. At $135 it is one of the less expensive kits I have had, but also comes with just the board. If you want a case that needs to be 3D Printed (more on that later).

ReActiveMicro points you over to the Project Wiki for more information, there is a ton there and a link to someone putting the project together. I found this easier to follow along and do than reading the instructions.

The kit was fairly easy and straight forward; I ran into a few small issues around the PS/2 port since the solder points are close together. Getting the few connector ports in can be a bit difficult with a few tiny pins and getting them in the board. As long as you have patience, then you can get through it.

Some bad solder up top, but those are structural to hold plugs so…

I got it all together, and the board started the first try. I did have the same issue the person who made the video had; I was getting a lot of noise and characters added to the screen. I reflowed a lot of the sockets, and made sure all the socketed chips were fully seated. That cleared up the garbage at startup. The wiki also has some other notes on noise issues the board can show.

I also could not find a PS/2 keyboard in the house, and all the USB keyboards I had didn’t seem to like the USB->PS/2 Adapter. I am not very surprised by this because I didn’t have any very simple, older keyboards.

The USB port that is used for power is also a serial device for a PC/Mac. I plugged into that and got the serial driver working from SparkFun website, they produce the module. Then the output worked well, and I could enter BASIC on the board!

Case

I wanted to put the board in some sort of case, and after searching online I couldn’t find any. I thought I would throw something together quickly that I could put the board in. I took some measurements and threw together a V0 of the case. One small issue was I didn’t account for the RCA jack the video comes out of little let that sticks out. Instead of spending another 7 hours printing a new one, I used a little saw I have to cut a hole out.

Part of my thought of creating a case was to have something I could put the board in, then store it in a cabinet or shelf and not be worried that the board would get damaged. I also made a case that can go over the entire unit to protect it in storage.

Again, looking back small design things could have been changed, like flip the name of the project in the case, so looking at it in the protective cover, the text would be right right way. Getting the scaffolding out of the protective case was not the easiest of things. I designed the protective case with a rail that brings the edge of the mounting board into a locking position when you slide it in. I have to say, that was a nice aspect to the design. It took over 6 hours to print though.

Link to case: https://www.thingiverse.com/thing:4819716

IMSAI 8080 Replica Kit

Continuing the journey of retro computer kits, I emailed the creator of the IMSAI 8080 kit over at https://thehighnibble.com/imsai8080/#overview when I saw the kit he had, but didn’t know if any were available; then one day out of the blue get an email saying a kit is ready for order! They come out in batches, this makes it take a bit to get them sometimes. To start off I can say this is one of the more well put together kits I have gotten. I was a little worried when I looked at the instructions and it mentioned a lot of part numbers and no photos of the setup; then I realized I had missed a link to a video that walks through the whole process, making it much easier.

The Kit

The kit is one of the more professionally put together kits I have done. From the metal case the system sits in, to the cut out cardboard all the parts come in. The creator, Dave, put a lot of attention to detail into everything. This kit includes everything from serial console lines on the back, to the micro controller having a WiFi antenna, which you can access over WiFi. The shipping box is also the correct size for the unit, you can use it as storage after you are done with the project. This kit comes with what you need ready to go and be put on the board (except solder and flux); some of the kits I have had in the past have required painting. You do pay a bit of a premium for it, but I think it is worth it. The kit also allows RS-232 connectivity or USB directly into the ESP32 controller.

Assembly

I will start off saying the hardest part of putting the kit together is at the beginning. There is a tiny chip for memory and that needs to be surface mounted to the board. This involves getting a small amount of solder onto the pads and then heating them with the chip on it. I accidentally bridged 2 pads and spent a chunk of time getting the tiny amount of solder off. After that part is over, you move onto the micro SD card reader, this is a similar surface mount; yet either I got better after doing the first one or got lucky, that was put down relatively quickly.

There is a diagnostic program you can run at that point to check if what you have soldered so far is working (which is fantastic), after that it is time for you to press on to soldering all the LEDs and their corresponding pieces. This part of the process is much like other kits of this type you may have done. It takes a while, but is a straight forward process.

In the end you sandwich the board together, and get it screwed into the case. There are a few parts where its gets a little tricky if you don’t want to have to pull the whole thing apart, but the video guide easily walks you through it.

Parts for controller
Controller with legs
Controller with legs
Socket mount
SD card mount
Controller is in and running diagnostics!
Back of board
Back of board without parts on yet
Back, with little done
Back with sockets in
Chip goes here
Taping down sockets to solder in
Some LEDs are done!
Lots of LEDs
Close up front shots
Front coming together
More front
Front without switches
Back, showing between layers
Back without clear acrylic on
Front without finished case
Finished back of unit
Controller through back
Back with controller, sd card, and reset button

Software

The software for the unit is great; the projects website, thehighnibble.com has instructions on how to use it. Similar to other projects there are certain switches you can flip to send the system different commands. But then, my favorite part is you can connect to the device over WiFi (either adhoc or with a AP) and then see the terminal. This allows you to leave the system on a shelf or a desk, and play with it at the same time. This interface also allows you to edit which “disks” are inserted into the system, to easily change images.

Overall it was a very enjoyable kit, other than the first little bit with the surface mounts. I think any beginner could do it once it is past that point. The resistor and LED soldering is straight forward. The metal case, and back clear acrylic make it stand out and look great. The WiFi and web interface put it over the top, as a it you can play with and connect to easily.