Hello chip dippers!
In a recent video, I showed you this
It's the Plus/4 Mini!
But although the Plus/4 Mini was just a big April Fool.. like me
I got a ton of comments from people saying that they wished it wasn't
They actually wished it was real
But you might not know, unless you watched 'Let's Explore the Plus/4'
Is there actually was a Plus/4 mini
Of sorts
It's the Commodore 116
Basically, a 16KB Commodore C16
In a miniaturized version of the Plus/4 casing
And designed, again, by Ira Velinski
And if you haven't heard of the C116 before
It might be because it was mainly only sold in Germany and Hungary
However, I never want to leave you hungry
So um thanks, thanks to a friend of the channel, Pete, we've found one
Well, I mean sort of
Yeah, not only is it missing his keys but it generates no picture whatsoever
Oh dear..
Well, let's team up with guest chef Pete, AKA...
Send this dish back to the kitchen for re-firing
See if we can end up with a Plus/4 Mini that's good enough to eat
Well, I mean.. to type on
Welcome to Retro Recipes!
In 'Let's Explore the Plus/4'
We discovered that the Plus/4 and C11 6 were part of Commodore's 264 series
Which included the 264, AKA Plus/4
Do you sell the Commodore Plus/4?
We stopped selling that when I was like minus 7 years old back in the 80's... '85
That's quite recently then
Oh, no, not too far off then
And the range included the Commodore C16
The Commodore 364 which was never released
(computer talking) I can say garple.
And of course, our C116, not our RC just C
And this range was announced that the recent CES in 1983 by Jack Trammell himself
Who sadly passed away on April 8, 2012
So, on this anniversary week of his passing, let's do him and these machines proud and bring this one back to life
So, I mentioned in the intro that this machine was putting out no video signal
Well, that wasn't quite the full story
In fact, there was nowhere to plug the video cable in
And if we open it up we can see why
It looks like a previous owner removed the RF modulator altogether
So it's no wonder we can't get a picture
But luckily we have a spare
So I soldered that back into place
And reconnect this one trace at the bottom right
Looking A-OK
Also, we need to replace the voltage regulator that had some problems
Nice!
Well, with that work done, let's turn it on and see what we get
Oh.. no, nothing
Well, there's a reason for that
See somebody has removed the TED chip from this machine
And here's a reminder of what that same TED chip does, this time in the Plus/4
It also boasted the superior MOS technologies
Lovely-li-lily named TED
All-in-one video sound and IO chip
Instead of the separate VIC II and SID chips of the Commodore 64
And the TED, meaning text display, had an impressive 121 colors
Almost unprecedented for the time
Now save your boos.. there's another problem
In testing the processor, this time the 8501 in the C116, in another machine
It turned out to be faulty
So we'll pop that out
Literally..
Unfortunately, we don't have a replacement but we may have another solution
But while I'm on the subject of the CPU
It's interesting that some people compared the C116 to the ZX Spectrum
That's because it's identical rubber keys or the lack of hardware sprites
But, in fact, the Spectrum was over twice as fast
And speaking of faster processors
This is the 6510 from a Commodore 64
And we found a little hack that will allow us to use that in place of the A501 in the Commodore 116-4
Let's turn it on again
Alright, so now the machine is in monitor mode
And what this means is that everything's working
But it's not displaying a basic prompt
And if it's not displaying a basic prompt
Well, the culprit is probably the BASIC chip
Now, unfortunately again, we don't have a spare one of those
But what we do have is this blank chip, which everyone knows is the W27c512
Right?
Well, anyway, we just flash BASIC to that blank chip and we're back to BASIC
Yay!
Come on kids..
We've got over 12,000 bytes free
Wow..
What we could do with all of that memory
Well, everything's now working on the PCB, but what about that keyboard?
Yeah, this is the real challenge here
How much, though, I wish we were missing zero keys
Freshly missing the 0 key
As well as X, SHIFT, and of all things the Commodore key
Sorry Jack!
So, as we open things up here
We can see about the previous owner has tried to repair some of these struts that hold this keyboard support frame in place
Using a soldering iron
And has left a bit of a charred mess
So we'll do a bit of a better job on that
Hopefully
But to understand how this all fits together
Let's blow things up with an exploded view
Not literally..
Seeing how much went into that, it's incredible to think that they retail this at 99 pounds in the UK
But as you also saw in there
This piece here is the keyboard PCP
And it's what makes contact with the keys or the keys make contact with
In this case the owner's tried to improve that conductivity
But it's gonna be crazy with the sandpaper
What wasn't such a crazy idea as they use these you bent copper staple kind of things
To also improve conductivity on the pad side under the key
But over time that copper has corroded or oxidized and now looks more like this
Which explains why most of the keys probably weren't working at all
So we'll take those out
What we're gonna do is get these little conductive pads that are used to repair TV remote controls
And they just fit perfectly on to the original pads of the C116
We'll also just soften out some of that sandpapering work with a finer sandpaper
And finally we'll use some PVB Varnish around the non-conductive areas just to tidy things up
And now the moment you've all been waiting for
Those keys!
Here's where the fun begins!
In just a moment
There is no spoon
Apart from this one
Yep. This is a plaster mix and we're gonna mix this up to make a mold
You see, I think somebody removed these keys to repopulate another machine
And that's just not good enough
So we're gonna put them back
We'll start off by putting electrical tape under the holes
And we choose that because it adheres really well to the rubber
Next we use some 3M Foam Tape to create a barrier or a dam or a reservoir
Dam whoever did this!
And we use Hot Snot or the Snot of Gods to secure it in place
Yep, we're a big fan of hot glue here Retro Recipes
And then here's our plaster mix
Speaking of recipes kind of looks like Greek yogurt
Or should I say (American accent) yogurt?
That reminds me someone actually once threw yogurt at me
I turned to my friend next to me and I said 'how dairy?!'
No, I was actually really angry. I'm lactose intolerant
But let's hope this keyboard isn't
We just pour the (American accent) yogurt.. plaster mix.. into the reservoir
And here it is just a few minutes later
We have a perfect negative impression of those rubber keys
So let's turn a negative into a positive
Where can he use a silicone rubber mix for this
And we ordered some medium gray dye to add to that mix
But as you can see, it was actually a very light gray
And with the mix already prepared we're gonna have to act fast to try to darken it
Which led to an idea
Hello
Ouch!
Yes, yes.. burned my hand
Yep, you guessed it.. charcoal!
So we'll grind this up in the Retro Recipe's pestle and mortar
And then add it to our silicone rubber mix
Hmm ..tasty!
And then we pour the mix into the mold with that 3M Tape around it again
Wait for it to set
And then later when we peel away the tape, we're left with this delicious looking slab
There's definitely a couple of usable candidates for keys in there
So we just cut around them so that they match the hole of the missing keys
Now, admittedly, getting a perfect color match is gonna be near on impossible
But these keys are gonna work
They feel the same
And they're gonna allow us to use this machine once again
And I can live with that
And there's all four of them in place
And then all we'll do is glue the undersides using some more of that silicon
However, the keys still didn't work right
And upon inspecting this ribbon cable that connects the C116 keyboard to the motherboard
We found this broken trace
So it's time for a quick repair job on the ribbon cable
But then the keyboard still didn't work right
And it turned out that this trace, this large trace here
If we look at it under the microscope
You can see that sanding job that the other user had done had actually broken this trace completely
So we can repair that with this piece of wire
If we hadn't been able to repair it and could have actually designed a whole new PCB
And sent it away to PCBWay to be printed
They still have a new year sale going on
And they're advanced PCBs are up to 30% off
And as we all know PCB stands for Pete's C116 Beauty
Doesn't it?
Well anyway is speaking of beauty. It's time to wrap up this project and put everything back together
Which means recreating these keyboards support struts
That the previous owner had tried to reinstate using his blowtorch
So with that in place and after we've given the case a nice rubdown and wash
Let's take a look at the before and afters
And all the keys now work perfectly
But I know what you're thinking..
What about the letters on the keys?
Well, that's where you come in
We want to know if you have any great solutions to reinstating that lettering
Without using things like stickers
Could be screen printing or or just a really steady hand with a pen
Or some other kind of printing method
Let us know what you think would work
And feel free to like and subscribe so you can follow any updates on this project
But more than that
What do you think about the real Plus/4 Mini?
Does it live up to its name of 116 which is considerably more than 64?
Or does it deserve its reputation as a lesser ZX Spectrum?
Not there's anything wrong with that
Comment below and Cheerio!