My Mini PET build

TomXP411 · Post by **TomXP411** » Mon Feb 21, 2022 11:44 pm

I recently built a Tynemouth Mini PET 40/80 from TWF8B. I enjoyed the build, and everyone who watched The 8-Bit Guy's review has already seen the high points of the machine. It operates very much like the original PET 2001, although with 32K of RAM and an optional 80 column mode.

TFW8B offers two versions of the Mini: an assembled PCB meant to go inside a case, and a stand-alone computer meant to show off the original "calculator" keyboard layout. I got the stand-alone kit, although I'm now wishing I had bought the internal PCB (I'd like to build it into a 64C case like T8BG did.)

Here are some pictures from the build:

The box is very reminiscent of the early Commodore products. I like it.

The keyboard is basically just two pieces of PCB material held together by two standoffs. This upper piece acts as a guide for the keycaps.

The bare PCB

And the assembled system. Above is the Commodore PET Demo, running off of the TWF8B SD2PET. (The file is included on the basic download package from their site.)

TomXP411 · Post by **TomXP411** » Mon Feb 21, 2022 11:55 pm

And the keyboard... I acquired the Petskey keyboard from Texelec, and I picked up the key switches from MechanicalKeyboards.com. For this build, you want "PCB Mount" switches. I went with Blue, because I like the feel of Blue keyswitches.

This is the bare PCB you get from Texelec. The space bar is done kind of weird... instead of using a stabilizer wire, Kevin designed the space bar with 3 key switches to keep it even. This results in a harder to press space bar, and I'm not totally thrilled with that design. I'm still considering getting a set of PCB mount stabilizers and drilling the needed holes in the board.

Here is the PCB with all the key switches installed. I made a frame for the keyboard out of wooden dowels, to allow me to set it on the desk and make use of a ribbon cable connector to connect the keyboard to the PET.

Here's the back of the keyboard. The dowels add the needed support and make the structure very sold.

I just bought a 40-pin IDE cable to use as a connecting cable. The keyboard itself uses a 20-position header, so I just use one side of the cable when hooking up the external keyboard. This works very well, and I'm excited to start using the Petskey keyboard, once the keycaps arrive.

Speaking of keycaps: I bought a set of Adafruit relegendable keycaps. I'll talk more about those when they arrive. Here's a link: https://www.adafruit.com/product/5039

The PET actually came with two sets of labels (just color printing on paper) so I'll probably use the second set for the Adafruit keycaps. That will give a nice, uniform look.

Scott Robison · Post by **Scott Robison** » Tue Feb 22, 2022 1:22 am

I like those keycaps.

TomXP411 · Post by **TomXP411** » Tue Feb 22, 2022 7:53 am

On 2/21/2022 at 5:22 PM, Scott Robison said:

I like those keycaps.

Yeah, I've been looking for something like that for a while. While they're not a perfect replacement for a full keyboard set, it's much easier to prototype custom keyboard layouts with something like that. I've also been thinking about building some sort of KIM-1 or Intel SDK-85 style computer, and having keycaps like that would make for a nice finishing touch.

TomXP411 · Post by **TomXP411** » Fri Feb 25, 2022 12:43 am

As promised, here's the finished keyboard. I elected to use square keys for everything, rather than wide keys for the modifiers, to stick closer to the original esthetic.

Now I'm going to spend some time tying on the machine, to see how comfortable it is.

John Chow Seymour · Post by **John Chow Seymour** » Sat Feb 26, 2022 6:14 am

It all looks great, thanks for sharing. I see you have some spaces in your space bar! That was probably a good way to handle that, given the circumstances.

I actually rather like the look of that 'calculator' style case. I probably wouldn't like typing on it... but visually, it sure looks cool.

TomXP411 · Post by **TomXP411** » Sat Feb 26, 2022 7:51 pm

On 2/25/2022 at 10:14 PM, John Chow Seymour said:

It all looks great, thanks for sharing. I see you have some spaces in your space bar! That was probably a good way to handle that, given the circumstances.

Surprisingly, the split space bar isn't a problem to use. All 5 of the keys down there send a space, so I find myself naturally hitting the key closest to the side my hand is on. I'm actually having more of a problem with the size of the keycaps. Standard OEM profile keycaps are a little bit narrower, and I find I make more typos on this than on my normal keyboard. Regardless, it's a fun toy to use and play with, and I plan to spend some time later building a complete assembly language toolchain on the system.

Strider · Post by **Strider** » Sun Feb 27, 2022 12:55 am

Now that I actually have a few days off and can actually DO stuff...

Excellent build!

I must have looked at that kit a hundred times, it looks like so much fun. I just can't fit one in my time space continuum at the moment. ?

The keyboard is looking really nice as well! I have been looking into building or modifying a keyboard to fit into a small space for a Pi project I have in mind, but that's on the back burner until I am all done with what's currently on my plate.

TomXP411 · Post by **TomXP411** » Mon Feb 28, 2022 6:36 pm

On 2/26/2022 at 4:55 PM, Strider said:

Now that I actually have a few days off and can actually DO stuff...

Excellent build!

I must have looked at that kit a hundred times, it looks like so much fun. I just can't fit one in my time space continuum at the moment. ?

The keyboard is looking really nice as well! I have been looking into building or modifying a keyboard to fit into a small space for a Pi project I have in mind, but that's on the back burner until I am all done with what's currently on my plate.

The keyboard is obviously customized for the Pet, but there's no reason you could not use it for a Pi build. In fact, with a nice 3D printed case, I can imagine this being a very nice custom keyboard for Pi or microcontroller based projects.

Strider · Post by **Strider** » Mon Feb 28, 2022 7:10 pm

On 2/28/2022 at 12:36 PM, TomXP411 said:

The keyboard is obviously customized for the Pet, but there's no reason you could not use it for a Pi build. In fact, with a nice 3D printed case, I can imagine this being a very nice custom keyboard for Pi or microcontroller based projects.

If my 3D printing aspirations work out, I was thinking of eventually building my own Pi 4 based "Retro" computer, once prices and stock return to some form of normalcy, whenever that may be.

I have no intentions of doing a full 3D printed case, but using prints to modify some sort of existing small enclosure to fit my idea and look "retro" once it's all done.

If not one of these cases, then something similar, but you get the idea.

https://www.amazon.com/dp/B005T8VDH2/ / https://www.amazon.com/dp/B005T6GCZM/ / https://www.amazon.com/dp/B005T592P0/

I just want to keep it small, at the hardest part of that will be the keyboard, and all I know so far is it will be 10-keyless. My only two real options will be to modify a small one that's already close to my needed dimensions, or make one, something I have never done. Thankfully, all the parts are out there these days to build your own keyboards. Either way, it should be a fun project, once I can find the time to get started on it.