Hello, and welcome back to The 8-Bit Guy.
So, in this episode, I'm going to assemble the PE6502 computer.
This is a hobbyist computer that's meant to be assembled at home, and this is actually
a prototype.
This computer is supposed to be Apple 1 compatible so you should be able to run Apple 1 software
on it and BASIC and stuff like that.
However, I spent a couple of hours talking with Jason on the phone, he's the guy that
designed this.
And he said he likes to call it Apple 1.5 compatible.
Because it's a bit more powerful than an Apple 1 but now quite an Apple 2.
But, what's really interesting is that what he's actually working on now is making some
changes that will allow this to run Commodore BASIC.
And have the entire Commodore screen editor and everything, which I think would be really
cool.
So, but I'm going to go ahead and put this one together and see what I can get running
on it.
I'll hook it up to my little handy TV here and I don't know, let's assemble it and
see if we can make it work!bThese zip-lock bags should have all of the components to
build this computer.
Let's take them out and have a look at them.
I'm not sure if there is any rhyme or reason to the way these are packaged.
Some things are grouped together in bags.
It looks like all of the smaller components are in this bag.
Here's the actual board.
It's really nice and well made.
That's definitely a lot of parts to solder!
Well, I guess I had better get out the soldering station and all of my tools.
But I also decided to print out the manual as it was difficult to reference it quickly
on my computer.
It's quite a few pages, so I printed it double sided to make it easier to manage.
All right, so I've got my soldering iron, I've got the manual, and the board here.
I also need a multi meter.
One of the main reasons I need the multi meter is for all of these resistors, because guess
what?
I can't read the codes on these resistors.
It's great that he even included the color charts for the resistors, but the problem
is I'm color blind and can rarely distinguish brown from green or violet from blue.
I can see most of the other colors in the spectrum, but it's really hard for me to
see brown and violet.
So, I can use the meter to measure the resistors so I make sure I use the right ones in the
right places.
It's also handy to have a picture here of the final assembly because sometimes that's
more helpful than a diagram.
I'm actually going to start with the resistors because they are the most challenging for
me due to my color blindness and I'd just like to get them over with.
And please don't send me a million emails about those special sunglasses for colorblind
people.
Now, the good news is, a lot of these are fairly obvious which value they are even without
the multi meter because I can tell that, hey, these 10 are obviously all of the same, and
so I can look on the bill of materials and see there are 10 identical resistors here,
so I know which ones these are.
And the same with these 7 here.
So that just leaves these for me to measure.
So I'll start with these 10 here, and the way I'm going to do this is just to use
the bill of materials.
So let's look at all of these 1 kilo-ohm resistors and I'll just start with this
one which is R2.
So I'll just look on the board and I can clearly see R2 here.
Pity there's no D2, right?
Then we'd have R2D2.
Ha Ha.
Anyway, that's pretty much where all of those 1K resistors go.
So I'll put all of those in.
Resistors are pretty easy to install.
Just bend the leads over like this.
It doesn't really matter which direction they go in, but it is nice to try to put all
of them the same direction so it looks professional.
Once in the hole, I usually bend the leads out just a bit so it doesn't fall back through
while I'm soldering.
I'm still waiting on my soldering station to warm up.
I forgot to turn it on earlier.
I'm using the default setting of 750 degrees.
There we go, all ready!
And, in case I've never mentioned this, soldering while trying to record it with a
camera is actually really difficult because you've got to get just the right angle to
see the action, and make sure your hands and other objects are out of the way.
I'm often contorting my body to accommodate the tripod.
So, doing this without filming is much easier.
So, when you see me shaking it's not because I am coming down with Parkinson's disease,
it's simply because I'm probably in an awkward position when I'm trying to record
it.
OK, this is what good solder joints should look like.
Afterwords, you can use some cutters to remove the excess leads.
So, now I just have a bunch more resistors to do.
Every time I put in a component, I mark it off the list so I know it's done.
All right, so I've managed to install all of these resistors here and over here just
by using reasoning without having to measure anything or being able to read the codes.
These are all that's left and I'll have to measure them.
OK fast forward a bit, and I've done all of the resistors now.
Notice I put them all in the same direction, which makes it look nicer.
For me, this was the most apprehensive part of this project, so everything else should
be a piece of cake!
The next challenge is going to be all of these tiny capacitors.
Now the thing is, the text on these guys is really small.
And my 42 year old eyes cannot read anything this small anymore.
So I'll be using this magnifying glass.
This one is really handy because it has a built in LED light.
Anyway, as you can see, it will bring these numbers into sharp focus, even for me!
The good news is, these capacitors are apparently all the same values.
The bad news is, they don't fit quite right into the holes.
The leads are too close together.
So that's about as far down as it wants to slide.
This is not uncommon, actually.
The solution is to bend the leads a bit like this.
And so, yeah, it will go in a lot further now.
And so that's how it looks after being soldered in place.
It's not perfect, but it will work.
And so here's all of the little capacitors now finished.
Next up is this resistor pack.
Basically it has 6 identical resistors inside which share a common lead.
And if you see that little dot on the left, that represents pin 1.
And if you look on the board here, pin one is also labeled so you know which direction
to put this.
So we'll just stick that in there, and solder that from the other side.
You sort of need 3 hands to install one of these, but the way I usually do this is I
hold the resistor pack from the other side with one hand, then I'll bend my lead of
solder out so it sort of holds itself near the place I need to solder like this, and
just bring the whole board to the solder.
All I need to do is get one pin soldered so that it will hold it in place.
Then the rest of the pins are easy to do.
I should mention, by the way, that I tend to like to install low-profile parts on a
board first, before I install any taller parts.
So that's just my preference, but it seems to make it easier because the board will lay
mostly flat and also because the smaller parts won't get in the way of the big parts when
it is time to insert them.
All right, so the next part I'm going to install is this 1 Mhz oscillator.
This is what runs the clock on the 6502 processor.
You may be wondering how to tell which direction it goes.
Well, if you look, there's this little circle here, that represents pin 1.
And of course, pin 1 is clearly marked on the board.
So it just goes in nice and easy, like this.
After soldering, these are a bit too long, so I'm going to cut them off.
And next up is the 5 Mhz Crystal used for the Parallax Propeller chip.
This has no specific orientation, you can put it in either direction.
And this fits in nice and flat.
There's exactly one diode in this project, and here it is.
There's a stripe on the right side, which indicates the polarity.
The good news is, this board is labelled really well.
Notice D1, that's where the diode goes and there's a little stripe on the diagram.
This will be pretty similar to the resistor in that the leads get bent like so.
And then right down it goes!
There's also exactly one transistor in this build.
Now, the only thing you need to know in this case, is that the transistor has a flat side.
If you look at the board, it goes right there, labelled Q1.
And you can clearly see the flat side.
The problem is the center lead will need to be bent out some.
So I usually just bend the lead out like this.
Then I'll use some needle nose pliers to bent it back down like this.
So now, it should fit in there better.
Yeah, actually it fits great!
So, I'll check that off the list.
Moving on, the next thing are these two momentary switches, used for reset switches.
One of them goes here, for resetting the propeller chip, and the other goes over here for resetting
the CPU.
Now, these look kind of square like they might go in more than one direction, but they are
actually slightly rectangular and will only fit one direction, so don't worry about
that.
Once it is lined up, it does take a bit of force to pop it down.
The next thing I'm going to solder in is this pin header.
Now, I will warn you that these are copper all the way from one side to the other.
So if you are holding this from one side while you solder it from the other, it will conduct
the heat really well and you're going to burn your finger.
So, this goes right here.
I suggest you be very aware which pins you are touching when you go to solder this in!
Of course, once you get the first pin soldered, the rest of them are easy to do.
Next up, I'm going to start installing the sockets, starting with these little ones.
With any socket, be sure to double check this little notch and make sure it lines up with
a similar looking notch on the board.
OK, so fast forwarding a bit, I've got that one installed, and that one installed, however,
I've got all of these sockets left to do.
These are going to be some of the most time consuming parts to install.
I tend to hold these with one hand, and I do sort of like I did with the resistor pack,
where I just put the solder right where I need it to get that first pin done.
Once that's done, I turn the board around and solder the opposite pin on that socket.
OK, so I've got each corner soldered.
And these aren't even very good solder joints.
But that's okay because they will hold it in place long enough for me to get some other
pins soldered.
At this point, I just want to double check the board from all directions that the socket
is in flat and that it is facing the right direction.
This would be a real pain to fix later.
Now I can solder the rest of the pins.
I'll take this opportunity to mention that I wouldn't really suggest a board like this
for your very first soldering project.
I'd suggest something smaller and cheaper.
But if you're a bit inexperienced, doing a board like this is going to give you a lot
of practice.
I would also like to mention I get a lot of requests to make a tutorial on how to solder.
But, honestly, there are several other youtube channels that have that covered pretty well.
I usually recommend a video by EEVBlog, which I think covers about everything you need to
know.
I will also mention that I'm using lead-based solder, which in my opinion is easier to work
with and does a better job.
However, I do have a fan going in the room that helps to blow the fumes away from my
face.
I also always wash my hands when I'm done soldering to remove any residue from my hands.
And some people might wonder why anyone would want to assemble this stuff on their own.
Well, to be honest, that's half of the fun of a project like this.
It's sort of like a jig-saw puzzle for nerds.
It will take you a few hours to assemble this and then there's the anticipation of whether
or not it will work when it is done!
OK, so I've got a problem.
These are the only pieces I have left, and I am missing a socket, which goes right here
for the MAX232, which is the serial port controller.
So, I guess what I'm going to do is just solder that chip in directly.
Which, is fine.
I mean, you don't have to have a socket.
The main benefit of a socket is to make it easy to remove if you fry the chip or for
whatever reason you might want to remove it.
But we have sockets for all of the rest of the chips, so I think we'll be fine.
OK, so now I'm going to start installing some of the taller objects, such as this header
for the system bus.
One problem you might notice is that… he he, gee it's too big to fit.
So no problem.
I'll just use some cutters and cut it to the right size.
And there we go, fits perfectly now!
Next I'll do the PS/2 keyboard connector.
PS/2 is kind of obsolete now, but at least they were made in the millions so they should
still be pretty easy to find.
Anyway, so that goes on like so.
And this is the next thing I'm going to put in.
This is the composite video connector.
This is where the TV or monitor will connect.
This thing has some pretty big pins on it, that's to help with the stress of plugging
and unplugging those cables.
And the last of the connectors is the DC power port, which is a fairly standard barrel connector.
I should mention this kit does not come with a power supply.
Anyway, so the connector goes here.
Like so.
And this thing also has some rather large pins to help with the stress of connecting
and disconnecting those cables.
I can't tell you how many laptops I've seen in my life that had broken power ports,
usually because somebody tripped over the wire.
Moving along, this is the power LED.
Now, you'll notice that one leg here is longer than the other.
And that is the positive lead.
And when you look on the board, you'll notice a flat side, and that is for the negative.
So the shorter leg will go in that side, like so.
Next up are two voltage regulators.
One of these is for 5 volts for the 6502, and then a 3.3 volt version for the propeller
chip.
Just line up the flat side with the big white line there.
Easy peasy.
One of the last things left to do is install these electrolytic capacitors.
I'm going to start with this big one here.
These do have a specific polarity so you need to make sure you don't put them in backwards.
You'll notice there is a stripe on this one side here.
And that needs to line up with the stripe on the board.
Now this board is different from any other I've seen when it comes to electrolytic
caps.
So, this cap goes in C21, but it is drawn as a square on the board.
I'm thinking maybe he originally planned to use tantalum capacitors or something.
Anyway, there is clearly a line showing where the stripe goes so you can still line it up.
But, it fits in there perfectly.
I'll bend the leads out to make it easier to solder.
And the soldering is almost done for this job.
Notice there's this spot to solder in a switch, but no switch was actually included
in the kit.
This is if you wanted to add your own to whatever case you might mount this in.
For me, I'm just going to use some of these left over pins and solder those in.
Skipping ahead, those are in now, and I'll just use this jumper here to act as a switch
so that power is always on whenever the plug is inserted.
This would also make it really easy to connect a power switch in the future.
And here's all of the left over trash and excess leads from assembly.
Now, the only thing that is left is to take all of these chips and insert them into the
sockets.
So, let's get started!
I'm going to start with the 6502.
Believe it or not, this is a brand new chip, Western Digital still makes these, although
I have no idea what uses them these days.
But this is definitely the newest 6502 I've ever held in my hands.
Now I'm going to put this in the socket.
I've actually bent the pins in just slightly to help them line up.
It's very important to make sure these pins are lined up really well, otherwise when you
go to push it down, one or more pins could bend or break off.
Same thing goes for these smaller chips, also be sure to double check the direction and
line up the notch!
This is the firmware ROM chip.
Let's put this in!
It takes a surprising amount of force to push these things in.
Next up is the propeller chip which will serve as a video display since you can no longer
buy the original Apple 1 video chips.
And this is a static RAM chip, I believe 32K, which is a lot more than the 4K of the original
Apple 1.
And THIS is a perfect example of pins not cooperating when I tried to insert the chip.
Fortunately, I caught it before I pushed it all the way down, so I can pull this out and
bend them back.
OK, so this thing is finally finished.
All that is left to do is test it!
I'm going to need a power supply.
I hope this is going to work.
It has the right connector and it's actually 6.5 volts, even though the instructions call
for 9V, this should actually work because it's rated for anything between 6.5 and
9 volts.
This actually comes from my speak and spell.
Anyway, I think it's going to work.
And of course, we'll need a standard composite video cable.
And I'm going to use this old PS/2 keyboard.
It's the perfect size for this project.
So I'll plug in the keyboard, and then I'll plug in the composite video cable.
And now it is time for the smoke test.
If I did anything catastrophically wrong, this is when I'll find out.
Well, the good news is, nothing smoked or popped.
The bad news is, there's no video display.
The power LED did come on, though.
OK, so I am not terribly surprised that it didn't work.
In fact, I would have been more surprised if it had worked the first time.
There's always some little detail an an assembly like this that's going to keep
something from working, even the tiniest little thing can keep it from booting.
But, you know I'm pretty sure I can get this to work.
So, I'm going to go ahead and start some of my standard troubleshooting techniques.
The first thing I wanted to do is check the voltage at one of the chips to make sure we're
getting a steady 5V.
And we are.
So the power supply and regulator and all of that is working fine.
The next thing I did was swap out this serial eprom for the propeller chip.
He sent me two of these for some reason, so let me try the second one.
And behold!
It actually works.
Well, sort of.
I entered into BASIC and just wanted to type something, sure syntax error, that's expected.
But then I discovered that any command I typed gave me a syntax error.
In fact, pretty much nothing worked right on this board.
It was very unstable!
It would reboot constantly like every few seconds, most commands I would type would
either give strange results or just cause the computer to reboot.
So, I knew something wasn't right.
I knew there had to be some other problem and I spent a lot of time troubleshooting
the board, and I couldn't really find anything wrong.
Now, the manual had said in here to clean all of the excess flux off the bottom of the
board and that is something I had intended to do.
But, you know, I was kind of in a hurry so I just thought, I'll skip that step for
now and I didn't realize how important of a step that is because flux apparently is
conductive.
And, I guess that never really occurred to me.
But yeah, so I took some alcohol and a toothbrush and I spent some time scrubbing the flux off
of the board and then I actually rinsed it in the sink and then it had to dry for a little
while, actually had to let it dry for several hours even after I used some compressed air
to blow all of the water off.
But after that, I turned it on, and it actually works perfectly!
It's perfectly stable now!
So, let's take a tour and see what we can do with this thing!
So, it boots up into something called wozmon, which stands for Wozniak Monitor.
It's a really simple operating system.
Just for some examples of what you can do.
If I type a memory address, like 2000, it will simply reply and tell me what byte is
stored at that address, in this case FC.
Of course this is all in hexadecimal.
If I wanted to see a large chunk of memory, I can type the address, then a period, and
then another address.
Then it will show me everything that is between those addresses.
There are two versions of BASIC stored in ROM, so I can start one of those up by typing
the starting address followed by an R. So, now I'm in integer BASIC.
Of course, I'm actually more comfortable in Applesoft BASIC, so I'll use that one
instead.
Of course, when demonstrating BASIC, everyone has to write a small looping command to print
something down the screen.
So I won't disappoint.
However, I'll write something maybe a little bit more interesting.
This is called a random maze.
We used to make these on the Commodore VIC-20 and 64.
It doesn't look quite as good here because the lines don't actually touch each other,
but you can still see the maze if you concentrate.
So you may be wondering what else you can do with it, since there are no disk drives
or SD card sockets or any way to copy over any other programs.
The original Apple 1 at least had a cassette port interface.
This doesn't even have that.
The only way to actually get new programs onto this computer is to type them in with
the keyboard either in BASIC or in machine code.
However, it does have a serial port, which can make that a lot easier.
So I'll just connect it up to one of my old MS-DOS laptops.
I was going to use my favorite terminal program, Telix, however, it doesn't seem to want
to run on this laptop.
So I'll just use Hyperterminal inside of Windows 95 instead.
According to the manual it needs to be set to 115,200 bits per second.
And it's working, because that READY is coming from the little computer.
OK, so what I'm going to do now is click transfer and send a text file over the serial
port.
I'm going to pick microchess.
As soon as I do this, you'll see this machine language code flying down the screen.
As far as the computer is concerned, somebody is typing this in on the keyboard.
It just so happens, the thing typing it is another computer, so it's really fast!
Once it's done, it automatically starts the game, as that's the last command in
the text file.
I've never played this before, so I'm not sure how it works.
I'll pick zero, I guess.
I have no idea what this means either.
And I can't figure out what I'm doing here either.
I guess somehow I'm supposed to indicate which piece I want to move.
Anyway, I'll have to read up on that later.
Moving on, you can also send BASIC programs much in the same way.
First, you just go into BASIC, in this case Applesoft Basic, and I'll send over a text
file for hangman.
Again, it's like I'm typing in the hangman game really fast.
However, when it is done, it errors out.
So I'm thinking maybe it was designed for integer BASIC instead, so I'll change over
to that version and then try it again.
Skipping ahead a bit… it works.
I'll guess E, nope.. how about S, nope.
U, maybe R, T, dang.. what is this?
Well, after nearly trying the whole alphabet, it turned out to be FLY.
Lovely.
Anyway, let's try another one.
This is checkers.
Again, I can't quite figure out the commands on this without reading the manual, so I'll
do that later.
All right, so I was not super impressed with any of the games that are available for this
little computer, so I thought I'll just write my own.
I was kind of thinking something along the lines of Tetris.
I figure I could probably write that in a few hours if I didn't try to get too fancy.
The trouble is, I couldn't figure out how to address the screen memory.
And documentation for the Apple 1 is a bit scarce and when you type that into google
you always get results for the Apple I devices like iPhones and iPads and stuff like that.
Eventually, with enough asking around I finally did find some documentation and one of the
things I discovered about the Apple 1 design which is really bizarre is that it's impossible
to actually address characters like anywhere on the screen you want.
So, the only thing that this computer can do is it can send characters one at a time
to a screen controller which will place the characters at the bottom of the screen and
then scroll everything else up.
But, it's actually impossible to come back up here and change some character that's
already on the screen.
The system's simply just not capable of doing that.
And, to illustrate why, I want to show you this little diagram, king of showing a rough
bus design of a traditional 8-bit computer that would have been made during the 1980s.
In a typical system of the 1980s, the CPU would talk with a peripheral interface adapter,
and that's usually what connects to things like keyboards, joysticks, and disk drives.
And then there's the ROM and RAM on the same bus with the CPU.
And then the video chip usually shares some of the RAM, and displays whatever it reads
on an external monitor.
The apple 1, however, has no joystick, no disk drive, and to be honest, no video chip.
At least not in the traditional sense.
What it does have is a rudimentary terminal display like you'd find in a dumb terminal
of the 70s.
And it is connected to the PIA chip, and the CPU just sends characters over to be displayed.
But the CPU has absolutely no control as to where on the screen the character will end
up.
That's all handled by those terminal chips.
Which means, coding a simple program like Tetris is essentially impossible on the Apple
1.
In fact, that explains a lot as to why those programs like the chess would always redraw
the entire board every time you make a move.
So that really limits what you can do with a computer like this.
However, it does have the full system bus available here on this pin header, so there's
no reason you couldn't attach some other kind of video chip, or even a little LCD screen
like this.
In fact, I may mess with getting one of these working for a future episode.
But still, you know it's a neat little computer, and especially with the expansion socket that
I mentioned, you could hack all kinds of things on there.
I mean heck, I bet you could get a SID chip to work on there if you wanted to!
But, I'll be much more impressed when somebody creates something really similar to this that
can run Commodore BASIC.
You know, the actually screen editor, and BASIC, and the Commodore kernel.
And it doesn't have to be compatible with the Commodore 64 or VIC-20, as long as it
can just run those things so that you can get the environment and you know you could
probably port over a lot of existing software, so that's something that I would have a
lot of fun playing with.
But, I do think it definitely needs and SD-card socket so that you can load and save programs
to something at least a little bit more modern.
I'd probably try to design it myself, but I simply don't have the time and it's
probably a little bit beyond my abilities.
Still, if anybody else has a neat little home-brew kit like this they'd like to send me, please,
contact me and tell me about it and you know, I may feature it here on the show in some
future episode.
Otherwise, I guess that about wraps it up for this one, so stick around and thanks for
watching!
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