Welcome back to the 8-Bit guy. So, when you watch documentaries about early
computer innovations, particularly the late 70s, early 1980s, most of the documentaries
tend to focus on Apple and Microsoft, and maybe IBM as the big innovators. But, I think often companies like Commodore,
and Atari, and Tandy don’t get nearly enough credit for the role that they played. Now, most of my viewers are familiar with
the Commodore 64, one of the best selling computers of all time. Well renowned for its great graphics and sound,
but Commodore history didn’t start with this machine. So, let’s go back a little bit to the late
70s and figure out where it all started! It all began in 1974 when Chuck Peddle and
a group of engineers started up a chip fabrication company called MOS Technology. Most of these guys had worked at Motorola
on their 6800 processor, and so they set out to develop a compatible CPU known as the 6501
that could simply be substituted for the much more expensive Motorola CPU. As you might imagine, Motorola sued and to
make a long story short, the 6502 was born, which was pretty much the same chip but changed
just enough that it was no longer completely compatible with the 6800. Of course, once it was no longer compatible
with the 6800, customers would need some way to test the chip out. In 1976 Chuck Peddle also designed the KIM-1
development computer. This was a single board computer that used
the 6502, and could be programmed in machine language from the keypad on the top. However, later it was possible to connect
a dumb-terminal display and actually run BASIC. Programs could be saved to a cassette tape. And, the computer proved to be popular with
hobbyists as well as engineers. The 6502 would go on to be a huge success
and eventually found its way into the Apple II series, the Atari 2600, the Nintendo Entertainment
System, The entire line of Atari 8-Bit computers, the BBC Micro, and of course the entire line
of Commodore 8-Bit machines too. But, going back to 1976 for the moment, MOS
Technologies was bought up by Commodore Business Machines, who at this point was primarily
in the calculator business. Chuck Peddle managed to convince Commodore
Boss Jack Tramiel that calculators were a dead-end business and that they needed to
produce a computer to compete with the upcoming Apple II. So, in 1977 the Commodore PET 2001 was born,
using much of the same design as the KIM-1. Much like the Apple II, the PET was all inclusive,
having an integrated monitor, keyboard, and cassette tape storage device. 1977 was a big year for the personal computer
revolution. With the market introduction of the big 3,
the Apple II, Commodore PET, and TRS-80 computer, this was the first time that a regular person
could buy an affordable computer without having to assemble it themselves. So one thing that is cool about the PET is
that it was actually designed by the same guy who designed the 6502 processor. And if you look at the prices of the big 3,
you’ll see the PET was competitively priced. Although the Apple II did have superior hardware,
which we’ll get into later, the PET did have the advantage that it came with a monitor
and tape drive, where the Apple II required those as separate purchases. So let’s take a closer look at the design
of the Commodore PET. The first thing I want to draw your attention
to is the keyboard. It’s insane, and it will drive you insane
if you actually try to type on it. One thing that isn’t communicated well by
video is just how small this keyboard is. The main part, excluding the number pad measures
6 inches by 2 and 3 quarters. Just to put that into perspective, my iPhone
6 will essentially cover the entire thing. If you take this apple mini keyboard, because,
yeah, this is supposed to be a miniature keyboard, it is actually huge by comparison. But the size isn’t the only problem. They layout is crazy. While the keys are technically in a QWERTY
arrangement, normally the rows are offset creating these diagonal lines like this. Not so on the PET. They are squared up. But the weirdness doesn’t end there. Look at this tiny space bar. And look at the top row of keys. Normally you would expect numbers to be here,
but there aren’t any. Instead you have just symbols. If you want to type a number, you have to
use the number pad. But what is even more infuriating is these
symbols. For example, if I want to type a Dollar sign
or a number sign, I would instinctively press shift before the key. However, when I do that I wind up with a totally
different character instead of the one I wanted. And then there’s the cursor keys. Notice that there are only 2 of them. One key goes down, and the other key goes
right. If you want to reverse that, you have to hold
down the shift key. So by using the combination of the cursor
keys and shift you can cursor anywhere on the screen. Oh and see this little back arrow here, you
might think that’s a backspace key. But, it’s not. It actually prints that character on the screen,
and so when you make a mistake, and believe me you will, you’ll going to go to push
this key and it’s not going to fix your mistake and you’re going to go even more
insane than you were before. The actual delete key is all the way over
here at the other side of the number pad. So, to be fair, when this computer came out
in 1977, most of the customers had never even used a personal computer before or a computer
of any kind. And so, they didn’t have any pre-conceptions
for what a keyboard layout should be like we do today. And so, it probably wasn’t quite as weird
for them as it would be for us. Let’s take a look inside the PET, it opens
like the cab of a semi truck, and even gives you a little kick stand to hold it open. Looking at these 16 RAM chips, you might think
the PET came with a lot of RAM. But, you’d be wrong. The original PET only came with 4K of RAM. These are 1K by 4-bit static RAM chips. Being that cost was such a consideration for
this computer, you might be wondering why they didn’t use the cheaper dynamic RAM,
or DRAM? Well, static ram was and still is today much
more expensive than dynamic RAM. However, DRAM has one drawback, it requires
that it is refreshed every so often, which requires additional circuitry to handle that. So, when you’re dealing with only 4K, it
actually ended up being cheaper just to use static RAM. So, 4K is a ridiculously small amount or RAM,
but it’s worse than that because the operating system actually needs at least 1K of that,
leaving about 3K left over for the user. So how much is 3K of RAM? Well, the screen on the pet is 40-characters
by 25 lines, meaning you need 1,000 bytes of RAM, or almost an entire kilobyte just
to store one screen full of text. So, essentially you had enough RAM for about
3 screenfuls of text. So, to be fair, though, the Apple II and TRS-80
only had 4K when they came out as well. This particular PET has been upgraded, that’s
what this little daughter board is here, it’s an aftermarket 32K RAM expansion module, and
that’s why it shows 31K available to BASIC on the boot screen. Let’s take a closer look at this cassette
drive. This was actually just an off-the-shelf cassette
recorder that Commodore bought and slightly modified. You can see the whole unit is actually mounted,
in a rather clunky way in my opinion, right here on the bottom. The cassette drive was really the only storage
device available for the PET at first. And with 4K of RAM, this wasn’t much of
a problem. It wasn’t until 1979 that Commodore came
out with a matching disk drive. Now, since the PET was never really designed
to use a disk drive, they decided to use the IEEE-488 parallel port as a means to connect
the disk drive. Now, unlike the Apple II, the Commodore PET
has no card slots inside so there’s nowhere to add a floppy disk controller card. So, what they had to do was essentially design
an entire computer inside the floppy drive unit, which would handle controlling the floppy
drives as well as an entire disk operating system. So, if you take a look inside the disk drive,
you’ll see it’s quite sophisticated, having it’s own 6502 processor, RAM, ROM, and I/O
controllers. The PET didn’t really interact with information
on the disks directly, rather it would send commands to the disk drive, such as telling
it to fetch a file, and then the disk drive would take care of all of the work of finding
the right data on the disk. In fact, it could even copy files or even
entire disks from one drive to the other all by itself, just with a single command. The PET was popular with schools and found
its way into many computer labs. And while the disk drive was expensive, one
of these floppy drive units could actually be connected to multiple PETs at the same
time, thus saving space and money. In fact, you can see this arrangement being
used in this photo from a computer lab where each table has 8 PETs connected to a single
floppy drive and printer. Let’s talk about the screen on the PET. The original model here is black and white. A lot of people assume it’s green, but that
actually wasn’t until later models. The original one was in fact black and white. In fact, there’s not even any grayscale. It’s just literally two colors, black and
white. The screen was controlled by a clone of the
Motorola 6845 CRT controller, which was also used in the IBM CGA card, among other computers. However, there was no circuitry here for color. There’s also no graphics modes. I mean, literally, none. No way to put graphics on this machine at
all. And what’s worse is that the character set
is in ROM and it cannot be moved, so there’s no way to modify what the characters look
like. So, you are pretty much stuck with putting
characters on the screen and only the characters that came built into ROM. And that’s it. However, there are 256 characters using a
special character set called PETASCII or later just shortened to PETSCII. The character set contains a lot of custom
symbols and can be used together to create rudimentary graphics. There are also a set of 16 block character
patterns that can be used to create rudimentary pixels. In fact, I wrote a program a while back called
PETDraw, which actually runs on the PET. It allows you to pick characters and place
them wherever you want on the screen. Of course, you don’t actually need a special
program to do this because the different characters are on the keyboard itself, all you have to
do is use the SHIFT key to type them. However, my program makes it easier, especially
if you’re using an emulator with a regular computer keyboard. Plus it has a special pixel draw mode that
automatically figures out which of the 16 block characters to use and allows you to
freely draw in a matrix of 80x50 pixels. This program is available for free on my website. The PET actually does have two character sets. I’ve been showing you the default, but if
you type POKE 59468,14 then it will switch to an upper/lower case set, which looks better
for typing, but has fewer graphics characters.The PET also had no sound.. I mean, like, literally none. There is no speaker and there’s no audio
output anywhere. However, early PET users figured out that
they could use two wires on the user-port, which connected to a handshake register on
one of the I/O controllers and it could essentially operate as a one-voice square wave generator. Soon after, many software programs started
using this method as the default method for sound production on this computer. Interestingly enough, the same concept will
actually work on any of the Commodore 8-Bit machines that has a user port, which is all
of them. However it was generally not needed because
all of these machines already have a sound synthesizer built in. Eventually Commodore redesigned the PET. For example, this 4016 model has a very similar
look, but you’ll notice the screen is quite a bit larger, and now uses a green phosphor
display instead of the black and white of the original model. The keyboard is redesigned so that it’s
easier to type on, however most of the weird key arrangement I mentioned earlier still
remains. The cassette drive is gone. At this point you’d have to use an external
cassette drive like this one, or a floppy drive. The case opens in a similar manner, but the
stand is in a different place. Also the case is now plastic, instead of the
metal found on the original PET. Also, they have included a speaker inside
the computer so it can produce sound without needing to connect anything to the user port. Notice this is a 4016, which basically means
it has a 40 column display with 16 kilobytes of RAM. Although this one has been upgraded to 32K,
which seemed to be the standard on later PETs. But they also had several different models
in this numbering scheme, with the high end models having 80 columns display and as much
as 96K of RAM. There were also some other weird variations
including one called a SuperPET. The PET would later evolve into Commodore’s
CBM line of business computers which kept a similar form factor, but much more ergonomic
with a detachable keyboard. I’ve never actually seen any of the CBM
line in person, as I think they were mostly sold in Europe. However, the 40-column PETs seem to have the
most software available for them. And, generally speaking, software designed
for the 40-columns won’t run on the 80-columns and vice-versa. Next I want to show you a cool feature of
Commodore BASIC. Using the screen editor, if I press a the
reverse key, it will change the text to reverse. I can press shift and reverse to disable that
feature. If I press the clear/home key by itself, it
will return the cursor to the top of the screen. If I hold down shift and press that key, it
will clear the screen. Now let’s see what happens if I use these
commands in a BASIC program. Once I type quotation marks, when I press
the clear key, it just leaves this little symbol. Then, I can type some text. Maybe use the reverse key. It leaves another little symbol. I can even use the cursor keys.” Now, when I go to execute this program, it
will actually remember all of the screen commands, which is cool because it makes formatting
text in your BASIC programs very simple! Speaking of BASIC, the PET used Microsoft
BASIC right from the beginning. And while the Apple II and TRS-80 did eventually
offer Microsoft BASIC, they both used proprietary forms of BASIC during the first year or two
on the market. And being that Microsoft BASIC was only design
in 1975, just 2 years before this machine came on the market, you could pretty easily
make the case that this was probably the first mass-market computer anyway, that actually
shipped with Microsoft BASIC. In fact, in the early PET models, if you typed
in WAIT 6502,1 it would show an Easter egg from Microsoft. In fact, if you change the second argument
in the command to a different number, it will display the Microsoft logo that many times. I’ve actually looked at the code and it
is clear that Microsoft essentially encrypted their name into this so that it could not
be easily found. Apparently Commodore was furious about this,
mostly because space was very limited on this machine and those Easter egg routines took
up precious space on a machine where every byte counts. Despite the limited graphics and sound capabilities,
there are no shortage of games for the PET. Most of the games were designed for the 40-column
version of the PET and there seems to be a lot of incompatibilities between PETs with
different keyboard types as well. This version of millipede is surprisingly
playable and enjoyable. As is this version of space invaders. Some of these graphics are so cleverly designed
using the built in character set, that you could almost be tricked into thinking these
were bit-mapped graphics. My friend Robin Harbron ported his RPG style
game minimae over to the PET as a fun project. There’s also a pretty darned good version
of Tetris available, and it even uses digitized sounds, but it requires a digital-to-analog
converter connected to the user port, similar to the Covox system that was available for
the IBM platform. The Commodore PET has also made it into the
demo scene a few times. Most notably this demo by ORB, which exploits
a new found way to display graphics on the PET. What they’re doing here is using some critical
timing to reset the video chip every scan line so that it only displays the top line
of every character. So by carefully using characters who’s top
row of pixels more or less match up with what they need, they can almost do pixel-perfect
bitmaps. This demo also exploits the use of a SID chip
if you happen to have one installed in your PET and then it would sound like this. Of course, Commodore never put SID chips in
the PET, but it is certainly possible to wire one in yourself if you want. Not that there’s a lot of software that
will support it, though. So, one mantra I’ve always had when talking
with inexperienced computer users who are afraid to try things on their computer. Is, I’ll aways tell them “Look, there’s
nothing you can do. Nothing you can type on this keyboard or click
with your mouse that can possibly damage the computer. The worst thing you could do is erase or corrupt
some data, and that can always be restored. However, it turns out in the case of the Commodore
PET, that advice is not always true. It was discovered that on certain models if
you typed the command POKE 59458,62 it would throw the CRT display out of sync, and after
a short time could actually damage some of the circuits and burn out the display. This was referred to as the KILLER POKE. So apparently my mantra doesn’t always hold
true after all. I think I’ll go ahead and test the killer
poke right here on this machine. After all, this isn’t mine, it actually
belongs to the Obsolete Geek. I’m borrowing it from him. Surely he won’t mind. Steve Gray decided to modify his PET so that
it could display color on an external monitor… and eventually integrated the color CRT inside
of the PET. This required extensive modifications to the
logic board and Kernal ROMs to make this possible, but it is certainly a neat project. The Commodore PET has also been featured in
countless movies and TV shows. Just to show a few of my favorite, you can
see one in Star Trek II, the wrath of Khan. It’s apparently part of Captain Kirk’s
antique collection. You can also clearly see one in many episodes
of the IT crowd. Apparently Steven Hawking used one as shown
in the movie The Theory of Everything. At the end of Terminator 3, when they arrive
at the fallout shelter, you can clearly see a Commodore PET behind John Connor. And in the movie Wayne’s World, the local
TV station has a Commodore PET in the office. So, the PET makes a great collector’s item. And, if you have room for one in your house,
they make a great thing to put on display. And it’s definitely a good conversation
starter when people come over to visit. But, truth be told they’re really not that
great of computers to actually use. And, I know a lot of vintage computer enthusiasts
and I don’t know anybody who really wants to spend hours on end sitting in front of
a PET. I mean, they’re pretty cool to look at,
and they have a really cool place in history, but they’re not really all that much fun
to actually use. So, in the next few episodes I’m going to
be covering the Commodore VIC-20, and the 64, Plus/4, 128, etc. And one of the things that you’re going
to see about those designs is that they were not revolutionary, rather they were evolutionary
from the PET. And you’re going to see a lot of technology
carried over to those machines. And so, many of the characteristics of those
machines can be traced back to their origins here at the PET or perhaps even further back
all the way to the KIM-1. So anyway, stick around for those episodes
and thanks for watching!
