Commodore Educator 64 Mini: Part 3

Here we are at the final article in the Commodore Educator 64 Mini series and there are a surprising number of loose ends to tie off; very probably the reason why it's taken a while to actually get around to documenting them.

This article more or less sums things up and provides some instruction on how get the project up and running. If you haven't read Part 1 or Part 2, I'd suggest starting from the beginning so that it all makes sense.

All files required to build the Educator Mini are made available at the end of the post.

The Final Product: The Commodore Educator 64 Mini

Fitting the Keyboard and Daughter Board

The keyboard is designed to sit quite firmly in the Educator case, it shouldn't require any glue but you may need to file and / or sand the 3D printed case lightly to gain that perfect fit.

The Raspberry PI Daughter Board and monitor cables should be fitted before placing the Raspberry Pi in it's Educator case, as there is not a lot of height to play with right up the back. Cabling running to the keyboard can be inserted at any time.

Educator Min Keyboard to Raspberry Pi Daughter Board / Interface

When fitting the keyboard you need to pay attention to the labels at the header pins. The numbers and letters correspond with a similar arrangement found on the PI Daughter Board. As a plus, the naming scheme also matches that used on a real 64 keyboard.

Commodore 64 Mini Keyboard fitted Snuggly: Pay attention to the jumper setting.

In addition there is a jumper setting to be made, for use in the Mini. A Jumper should be set across pins 1 & 2. The Jumper determines the behaviour of the Shift Lock key, unfortunately there are not enough free GIPO pins on the PI to take advantage of this feature for now.

Inside the Educator MIni

Finalising Model Styling

You'd have noticed by now that the Educator Mini 64 has a somewhat different set of stickers to Lorenzo's PET (much like the real thing really). I've made up a couple of additional mini replica decals to suit the 64, the most obvious of these being the BASIC reference panel.

The BASIC keyword panel is a fairly good approximation the original full sized version and depending on how good your eyes are and the resolution of the printers used to produce the decal sheet could well come in useful.

I've also included Lorenzo's decals for the back of the monitor and the Serial Number Name Plate for the sake of completeness.

Educator 64 Mini Decal Sheet, Including everything an old computer needs.

Getting the Educator Mini up and Running

RetroPie is normally your friend for an easy Linux retro solution. Disclaimer time, I decided not to use RetroPie for this build and went with a standard versions of Raspberry Pi OS (previously called Raspbian).

There are a number of reasons I'm using Raspbian, the main ones for me being,

1. It's just simpler to get the keyboard working with the Vice emulator.
2. I'm only intending to use Vice and Commodore Emulation on the Mini.

Of course your needs may vary, and what ever I've done is really only a suggestion.

Installing the Vice Emulator

Raspberry Pi OS does not include the Vice Emulator as a standard package, or even an optional downloadable package, so you'll need to install it manually. I simply followed the Installation guide on krystof.io 

Once Vice is installed you'll be wanting to add a configuration file to get the emulator looking and feeling right.

Run the following commands to create a sdl-vicerc config file:

mkdir -p ~/.config/vice
nano ~/.config/vice/sdl-vicerc

[C64SC]
MenuKey=293
MenuKeyUp=273
MenuKeyDown=274
MenuKeyLeft=276
MenuKeyRight=275
MenuKeyPageUp=280
MenuKeyPageDown=281
MenuKeyHome=278
MenuKeyEnd=279
WarpMode=0
Sound=1
SoundDeviceName="sdl"
SoundSampleRate=8000
SoundBufferSize=100
SoundFragmentSize=0
SoundVolume=100
SoundOutput=1
AspectRatio="1.000000"
SDLCustomWidth=480
SDLCustomHeight=320
SDLWindowWidth=480
SDLWindowHeight=320
SDLGLAspectMode=0
VirtualDevices=1
IECReset=1
CIA1Model=0
CIA2Model=0
VICIIVideoCache=1
VICIIDoubleScan=0
VICIIDoubleSize=0
VICIIFilter=0
VICIIModel=0
SidEngine=0
SidModel=0
JoyPort4Device=0
JoyDevice1=4
JoyDevice2=4
AutostartBasicLoad=1
AutostartPrgMode=0
DriveSoundEmulation=0
Drive8Type=1571
GlueLogic=0
ETHERNETCARTBase=56832
Acia1Base=56832
AutostartWarp=1
KeyboardMapping=1

Setting Up the keyboard

There are multiple was to of configuring a keyboard for use with the vice Emulator, I've chosen the path of least resistance. Feel free to delve deeper into the heavy customisation that Vice affords. That said intense configuring is a little above what's really required for what is essentially a very cute desk toy.

For the initial steps, we'll basically be following those documented in PJ Evens's MagPi issue 67 article on page 26, make some changes specifically for the Commodore Educator 64 keyboard.

1) install Libsuinput: From your home directory:

cd
sudo apt install get libudev-dev python-dev python-pip
sudo pip install wiringpi
cd git clone github.com/tuomasjjrasanen/libsuinput
cd libsuinput
./autogen
./configure
make
sudo make install

Add the following line to /etc/modules-load.d/modules.conf

uinput

2) Install Python-uinput: From your home directory:

cd
git clone github.com/
tuomasjjrasanen/pythonuinput
cd python-uinput
sudo python setup.py build
sudo python setup.py install

3) Install cbmscanner python scripts:  Download these scripts and uncompress the file. We'll mimic the original Magi Article and install them in a subdirectory off the home dir.

cd
wget  -P ~ "http://dasteph.com/cgi/pet/files/cbmscanner.tar"
tar -xvf cbmscanner.tar

4) Create a new Service: We need to setup a new service to run keyboard scanner on boot by creating a new config file.

sudo nano /usr/lib/systemd/cbmscanner.service

[Unit]
Description=Commodore 64 Keyboard Scanner
After=multi-user.target
 
[Service]
Type=simple
ExecStart=/usr/bin/python /home/pi/cbmscanner/cbmscanner.py
Restart=on-abort
 
[Install]
WantedBy=multi-user.target

sudo systemctl enable /usr/lib/systemd/cbmscanner.service

5) Configure Keyboard Layout: Edit the keyboard file and ensure we're setup for a US keyboard layout.

sudo nano /etc/default/keyboard

# KEYBOARD CONFIGURATION FILE
# Consult the keyboard(5) manual page.
 
XKBMODEL="pc105"
XKBLAYOUT="us"
XKBVARIANT=""
XKBOPTIONS=""
 
BACKSPACE="guess"

We can the reboot the Raspberry Pi, the keyboard should then work as intended.

All the Educator 64 Files to Download

• The 3D Model Files: Model changed for use with a PI 3A
• The PCB Gerber Files: Keyboard, PI daughter Board, Optional Monitor Plugin
• The Decals Set: Educator 64 Styling
• The Python Code: Keyboard Code (See above for required libraries)

Please be sure to refer back to the official  Commodore PET Mini site for the full build details and project history not covered in this series of blog articles.

See all entries for this project:  Part 1, Part 2 and Part 3

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Commodore Educator 64 Mini: Part 2

When I embarked on the Educator 64 journey I had no idea this would end up being my particular quarantine pass time. Who would have thought being stuck at home would be so useful.

So where are we up to? By the end of Part 1 I'd covered the printing of the Educator 64 Mini Case and very briefly mentioned sending a keyboard PCB of for manufacturing. This time around I'll get into the design of the keyboard and detail some additional modifications I've made to Lorenzo Herreras' Commodore PET Mini.

Mini Keyboards for Tiny LCDs

On the whole I've not diverted much from the general design of the Commodore PET MINI. The main inclusion is that of the working keyboard, I did however choose to make things slightly easier where possible in other respects.

As I was going to be ordering a PCB for the keyboard I decided I might as well design an extra PCB that would plug into the back of the LCD panel. Lorenzo's PET screen design has you dissecting a ribbon cable, then hand wiring the various bits to the back of the the Waveshare LCD screen. To much effort I thought, a nice little PCB would save all that hand rerouting trouble. I also thought mounting a reassuring yellow glowing LED at the back night add some CRT realism (or not, turned out you can't really see it once installed, oh well).

LCD Mounting PCB

I addition to the LCD mounting PCB I took the opportunity to deign and order a Pi Zero sized prototyping board which extended the pin header out and added had just enough space to the end of the board for some diodes and the like. The board was a bit of an after thought, although as it turned out I needed it.

Keyboard Design

There's no shortage of people out there hacking old Commodore 64s and making them work with modern equipment. One of the largest set of modifications to dead 64s is in the re-purposing of their keyboards for use with emulators.

To this end the schematics for the 64s keyboard are well know and have been pretty convincingly documented by Simon Inns on his page Waiting for Friday. Simon interestingly points out that the official Commodore Keyboard Schematic is wrong; that certainly spared me some confusion as not having a 64 myself I had nothing else to go by other than the published designs.

Commodore Educator 64 Mini Keyboard Circuit 

I made one minor change to the keyboard schematic; the inclusion of a jumper allowing the SHIFT LOCK key to be placed on the same Column as the Restore Key,  or in its normal state as an extra LEFT SHIFT key. On a Commodore 64 keyboard the SHIFT LOCK actually locks in place if pressed, this functionality isn't possible with the TAC switches I planned on using, so I opened the option to simulate that behaviour in software latter (This option wasn't to be, read on). 

With a known working layout for a Commodore keyboard to hand, all that need to be done was getting all to fit onto a 105x38mm PCB. As mentioned in Part 1 I'd found the perfectly sized switch in the KMR431G which has a footprint of 4.2mm x 2.8mm. The resulting layout mimics the design of a full sized Commodore keyboard. As there are to be no keycaps, Legends are printed on the PCB, some additional PCB styling gives the impression of a full space bar and a silk screened separator between the main keyboard and function keys implies the existence of the metal or plastic case shroud.

The Commodore Educator 64 Mini Keyboard PCB

Reading the Keyboard

My initial plan was to use an Arduino Proc Micro acting in HID mode for decoding the keyboard inputs and passing key presses onto the Pi. The other option I'd considered was procuring a Commodore USB Keyboard Kit from Tynemouth Software. Both of these methods required a spare USB port on the Raspberry PI, being that by this time I'd decided to us a Pi 3A+ for the project (which only has one port) I really didn't have a USB port to spare, particularly if I need to connect another device such as a joystick.

A long time ago for the AZ15 build I'd considered connecting a ZX81 matrix keyboard directly to a Pi, but thought the method a little to cumbersome and unreliable. What I couldn't find at the time was a good way of sending key presses back to the LINUX kernel, sure you could detect a keypad, but only in the active program doing the decoding, not much use for emulators. Fortunately time passes and things get developed and now there are off the shelf solutions.

Enter an article in The MagPi Page 25 by PJ Evans, where he describes, and provides many of the necessities required for reading a ZX Spectrum Keyboard directly, then injecting those key presses back into the LINUX kernel. This Sounded just the ticket for the Commodore Educator keyboard, All that's needed are some software libraries, libsuinput for handling the kernel injection, and wiringpi to run some keyboard scanning code. The only possible road block being the availability of enough free GPIO ports to handle the Commodore Keyboard.

Mapping Raspberry Pi GPIO pins to the Waveshare LCD and C64 Keyboard

At a minimum we need 17 free GPIO ports to read the c64 keyboard (without worrying about multiplexing), 8 Data lines, 8 Address lines and 1 for detecting the RESTORE key. In reality I has hoping for 18 spare GPIO pins so we could enable SHIFT LOCKing. After consulting the Waveshare LCD manual it appeared all requirements could be met, but appearances can be deceptive.

Out of 28 GPIO pins the LCD panel uses 8, leaving 20 pins. Not so fast, GPIO23 is taken when using analogue audio (which we need) and on testing I also found GPIO27 and GPIO22 also seemed to be in use by the LCD panel. That left 17 ports. However GPIO14 & 15 are used as serial lines, that's now down to 15 ports. Fortunately serial can be disabled in the /boot/config.txt file. Phew, we have just enough ports free without having to stuff around with multiplexing.

The rather messy prototyping Board full of Diodes

To get things moving along I wired up my prototyping PCB much as documented in The MagPi article, I adjusting the data and address lines (see earlier image above). I then downloaded the required zxscanner code by PJ Evens, modifying sufficiently to accommodate the C64 keyboard, the result a working keyboard.

Testing the tiny Commodore 64 Keyboard

That is of course just the start, I still need to go back though the zxscanner code and turn it into c64scanner code. As it stands zxscanner is just that, it's geared towards ZX Spectrum emulators, Commodore emulators such as Vice take a somewhat different path when mapping keys from PC-like keyboards and that is something we can tackle in Part 3.

C64 Keyboard Installed and some final Decals Added to the Case

Until the next article here's a quick preview of the keyboard in action:

See all entries for this project:  Part 1, Part 2 and Part 3

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Commodore Educator 64 Mini: Part 1

What do you do with a new 3D printer, a governmental advised quarantine stay at home order and the freely available plans for a Commodore PET Mini build? Why build a Commodore Educator 64 with a functional keyboard of course.

Printing your own PETs.

A  little over a year ago Lorenzo Herrera launched the Commodore Pet Mini on the world, a very cute miniature PET model 8032 housing a Raspberry Pi. Nicely he also included all the 3D models and a full material list so you could build your own (and a lot of people have). 

This all looked like a really fun project, the only problem being I didn't have 3D printer.  Then quite unexpectedly and just before the world locked down the family presented me a with a Flash Forge Finder 3D printer for my birthday. Thanks Family!

And so the initial stage of building a PET (soon to become an Educator 64) Mini began in earnest.

The Making of a Model

While the PET mini is quite the functional beauty as is, what with its Pi core, tiny LCD screen and USB ports, it does almost criminally lack the most important part of an early home / office / school computer, a functional keyboard.

Before going to far along the process of 3D printing I first need to know if I could get a keyboard to fit into the PET Mini. I managed to find some very diminutive KMR431G surface mount TAC switches on Element 14, tiny but not tiny enough to build a full PET keyboard.

The KMR431G switches would just squeeze in nicely when arranged in a 64 style. As luck would have it the Case design of the PET 8032 (and Lorenzo's 3D model) is near identical to that of a Educator 64. For those that don't know, an Educator 64 is basically a Commodore 64 in a PET case sold primarily to schools; possibly making it the best 80s game playing school computer ever.

Educator 64 Mini Keyboard PCB

I'll cover the full details of the keyboard and how it's intended to work in Part 2: For now though I laid out a PCB that followed the C64 key mappings and sent it off for Fabrication. The important part being that I now had the measurements required to adjust the top half of the PET case to fit the keyboard. 

Case Adjustments to be Made

To fit the keyboard into the Mini I simply cutout the keyboard space from the original model and designed a shelf for the new keyboard PCB to sit on. Additionally I removed the magnet clips which would normally be located under a printed keyboard and replaced these with clips located on either side of the modified case design.

Lorenzo provides bottom case templates for Raspberry Pi 2/3's and for the 4. I had a Pi 3A on hand and further modified the lower case to fit that in place. The shorter Pi 3A board would came in handy later when cramming many additional keyboard wires into the case. 

Exploded View of the Commodore Educator 64 Mini Case.

Unfortunately the cases main top and bottom sections proved slightly too large for my printer. So I broke these down into separate components with some additional tabs put in place to make gluing them together convenient  and providing some structural strength. I also decided to divide the monitor stand into a bottom an top piece facilitating slightly easier 3D printing and finishing.

The other large-ish change I made to the original model was in redesigning the monitor frame, that part holding the LCD panel. This I made this slightly wider and a little less ovaloid in keeping with the source material. The clasp holding the monitor in place I also reduced in size considerably, minimising the likelihood of snapping an LCD panel accidentally. 

Printing and Finishing the Model

With all the adjustments made the model printed out quite easily. Finishing the the plastics took a little extra effort.

From other modelling activities I had a set of small files and sandpaper which went to good use. Quite a lot of time went into smoothing of the rougher areas and obvious layering from the 3D printing process. I wasn't intent on removing all traces of the printing technique, the model should reflect the process at least to some extent. 

Once sanded down and finished, the little Educator 64  parts were spray painted with a couple of colour combinations. The white panels being a mix of Tamiya TS-26 Pure White for the under layers and TS-7 Racing White for the finishing coats, lending a nice retro feel as the Racing White is slightly creamy in colour.

The black areas of the model were first painted in Citadel Lead Belcher, although any steel or silvery colour would be just as fine (It just happened to be the colour I had available).  The top coat is a Tamiya TS-6 Matt Black, applied relatively lightly, just enough to appear black while allowing the metallic undercoat to maintain some presence. All the components were then sealed with a Satin Spray varnish. The end result being really quite pleasing.

Next Time: The Electronics

The Educator 64 fits together much as the PET mini. The major electronic components are pretty much listed at commodorepetmini.com. In Part 2 I'll attempt to go over how the keyboard is configured and how it works in conjunction with the original PET design.

See all entries for this project:  Part 1, Part 2 and Part 3

 

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