Fixing Gran Trak 10

This project started with an email from my old friend David Oliver. He had sold his warehouse in Seattle and all his games had to go.

Dave and I worked together as programmers on some of the early versions of Microsoft Word for Windows in the 1990s. Back then we shared a passion for pinball and had several machines stashed away in an unused office at work. Little did we know we were living through one of the greatest periods of pinball design in history. If you wander over to the Internet Pinball Database  you’ll see that the games we had in that office: “Twilight Zone”, “Addams Family” and “Star Trek: The Next Generation”, are among the highest rated pinball machines of all time.

Dave’s email divided his game collection into three categories: 1. Good games that worked at one point but might need a bit of fixing. 2. Good games that never worked but could be fixed. And 3. “Super old black and white games” that if I didn’t take off his hands were going into the dumpster. Fortunately I like “super old black and white games”, and, of course, rescuing and restoring these machines is the main point of this blog, so I told him to bring them on over.

Among the haul was a game I really wanted to work on next: Atari’s “Gran Trak 10” which released in March of 1974. This game has so many firsts it’s hard to list them all: First car racing video game. First video game with a steering wheel, gearshift and gas/brake pedals. First video game using a ROM (read only memory) chip. First video game using “hybrid” security chips. And, probably the first video game with a true 60hz interlaced display.


When Dave arrived he not only dropped off a complete (but completely not working) Gran Trak 10, but he also gave me a couple boxes full of parts he had salvaged from another Gran Trak years before. This gave me two of just about everything, including the rare 23 inch B&W Motorola XM-701 monitors used in these machines. Time to get to work!


(it looks like the game is running but that’s just the old image of the track burned into the monitor)

Fixing the Monitor(s)

The earliest arcade video games made by Atari and others simply used a modified television as their display. But with the success of Pong and the many clones that followed, Motorola saw an opportunity and began to produce monitors specifically aimed at this market. The 19 inch XM-501 and the 23 inch XM-701 were the result. I fixed a 501 for an Atari Anti-Aircraft (1975) a few months earlier so I wasn’t too worried about working on the 701. These monitors were made with repair in mind and have a few handy features. For example the entire chassis can be unplugged for easy access.

To fix the monitor I hooked up a known good video source: my 1973 Atari Space Race board:


Both monitors showed a pure white raster image that filled the majority of the screen. To me that meant that for the most part the monitor was working since it was properly tracing out horizontal lines, but the input was somehow not making it through to be displayed. This was the perfect chance to try out the new oscilloscope I recently picked up from Amazon:


See that blue “AUTO” button? More on that in a minute…


I rolled the monitor on its face so I could get to the bottom of the circuit board while it was running, hooked up a probe to the oscilloscope and started following the video signal through the board as I followed along on the schematic:


It turns out that video signals are pretty easy to recognize once you’ve seen a few of them, but getting them to display on the oscilloscope would normally involve a bunch of fiddling with all those knobs . That’s where the magic “AUTO” button comes in. Just stick your probe where you know there’s a good signal, push “AUTO” and let the oscilloscope figure out how to set the knobs. After a second or so you get an image like this:


The little spikes pointing downward are horizontal sync pulses that tell the monitor to return the electron beam to the beginning of the next line, kind of like hitting carriage return on an old typewriter. The spikes sticking up are individual pixels.

So I just started on the left of the schematic above and followed the signal along through the circuit board. Everything looked good through the first transistor but when it got to the variable resistor marked “Contrast” the signal stopped. I wiggled the contrast knob and voila! Now I had a signal coming out the other side, but the screen was still blank.

I continued to follow the signal into the second transistor (Q2) but lost it on the other side. Did that mean the transistor was bad? Maybe. But there could be other causes. I did a quick diode check on the transistor with my multimeter. Not always a reliable test when the transistor is still in the circuit but it made me think it was probably okay. So what else could be wrong?

Well there’s a big electrolytic capacitor (C6) right there. Those things go bad all the time on these old machines.


I checked it and sure enough it was a pure short to ground. After replacing it the screen looked like this:


Space Race! I hooked up the other monitor and, to make a long story short, it had the exact same problem with the exact same capacitor. With that fixed I had two working monitors. Time to move on to the game board, but first a brief intermission…

Gran Trak History Part 1

Gran Trak was designed by Atari’s research and development group in Grass Valley California. Formerly known as Cyan Engineering, they were ex-Ampex employees who had worked in the same group as Nolan Bushnell before striking out on their own to form Cyan. Cyan had consulted with Atari on projects going all the way back to Pong, before being acquired in the Summer of 1973.

The original idea for Gran Trak came from Cyan co-founder Steve Mayer. He was reading Scientific American one day and saw a Martin Gardner article about a pen and paper game called Racetrack:


As he says in my interview with him:

“This suggested to me that we could go ahead and do a driving game, you know, because driving games were always a staple of electromechanical coin-op so it was a very logical thing to look at replacing a mechanical arcade game with a video game.” – Steve Mayer

Fixing Sync

I pulled the printed circuit board out of the machine and boy was it dirty. I’m not normally picky about a little dust on a board but this thing was so bad I couldn’t even read the names of the chips. I decided I had to clean it before I could get to work. This was a little tricky because there were fine jumper wires in several places on the board that I wanted to make sure I didn’t break. In this image you can see what it looked like after a little cleaning in the corner:


And after cleaning the whole board:


The big filter capacitor you always find on these boards looked like it was oozing something out one end:


I decided the capacitor had to be replaced and ordered a new one online. In the meantime I pondered how I should hook up the board. Fortunately in Dave’s big box of parts was a complete wiring harness including a transformer and everything else I needed to plug it into the wall. I screwed the line voltage parts onto a board so they wouldn’t bump into each other, figured out which wires on the old harness were the video signals, hooked them up to one of the monitors, crossed my fingers and flipped on the power. This is what I saw:


Well that ain’t right. Not only was the image scrambled, as you can see, but it was also rolling wildly across the screen. Just to be sure there wasn’t just a vertical hold problem I hooked the output to a more modern monitor, but the result was the same:


When you see something like this it means that the board has a problem with the synchronization signals it is sending to the monitor. I wrote about the basics of this in my last story (Fixing Color Gotcha) so I won’t duplicate that here. The main point is a horizontal and a vertical counter circuit has to send appropriate signals at appropriate times to keep the image stable on the screen.

One great thing about working on this particular game is the manual is really good (Gran Trak 10 Manual). Not only does it include full schematics but it also takes subsets of the schematics for various functions of the board and describes how they work in English! This is luxurious compared to what I was used to with my last projects. That said, the sync circuit for this game is more complicated than what I had seen before. It looks like this:


So why is it so complicated? The short answer is because the output is “interlaced”. An old school TV monitor draws every other line, then returns to the top and draws another set of lines in between the first ones to create a full frame every 30th of a second. All the video games I know of before this one cheated and just had the monitor draw the same set of lines every 60th of a second. Doing it that way is easier to implement (requires less chips) but cuts the vertical resolution in half. That wasn’t good enough for the designers of Gran Trak 10:

“We did [the interlaced display] because we wanted to get smoother motion and so it was not so much for resolution of what we were drawing although that was important, but we wanted to be able to make the speed changes and the motion much smoother so that gave us 512 instead of 256 vertical lines and also increased the horizontal resolution so the motion was much smoother.” – Steve Mayer

On the schematic above you can see that there are things marked “TP”. Those are Test Points and for each one there is a handy description of what you should see using your logic probe and your oscilloscope. Unfortunately I tested them all and they were all working fine. That didn’t leave much else that could be wrong. If you look on the far right side of the schematic the horizontal and vertical signals pass through one last Exclusive OR gate before heading out as the “COMP SYNC” signal. Could that be the problem?

Before I pulled the chip off the board I decided to try a trick. What you do is take an identical chip to the one you think is bad and you stick it right on top, being careful to line up the pins correctly. This doesn’t always work, depending on what’s wrong with the bad chip, but it’s so easy to try, why not give it a shot?

So I carefully stacked the new chip on top of the old…


And… it works!


Okay, now to fix it right. Just pull off the old chip. Oh wait. There’s an old jumper wire running under it. These things were put on in the factory to fix problems with the printed circuit board layout. In this case I am working with “E” revision of the circuit board (more on that later) which, it turns out, is a very early version of the board.


I carefully clip the chip’s pins off, slide the jumper wire over, and, oh wait, there’s another jumper wire connected to one of the pins. This is going to be a little tricky:


Desolder the pins. Solder in a new socket, being careful to attach the jumper to the right pin. Looks pretty good:


Plug it in, turn it on, and… the screen is still messed up and flipping all over the place! Sigh… It’s moments like this when I recall my favorite line from The Rocky Horror Picture Show: “I have removed the cause, but not, the symptom!”

Okay, check all the solder joints. They are good. Check that I attached the old jumper wire correctly. It’s fine. The other old jumper is out of the way. It should be fine. Might as well check to see if it’s still a wire. Connect my meter from one side of the jumper to the other and… the wire is broken. Apparently a super thin 42 year old wire can break just by sliding it slightly to one side. Glad I was careful when I cleaned the board. Oh well, easy enough to fix. Put in my own jumper (yellow wire below) with some delicate soldering to some very old chips:


And… it works!


Well, the display works. The car doesn’t actually go or anything. You didn’t think it would be that easy did you?

Gran Trak History Part 2

Steve Mayer teamed up with Ron Milner (My Ron Milner Interview) to do most of the game design, and by game design I mean the two built the entire game from scratch using nothing more than primitive logic gates. But there was a third amigo on this team and he was Cyan co-founder Larry Emmons (My Larry Emmons Interview). Larry was, according to Steve, a “great analog engineer” and Larry thought this would be a good project for Atari to make their first hybrid analog chips. Chips that were to cause everyone at Atari (and even me) some amount of grief…

Fixing Making that Damn Car Go

After fixing the sync circuit I reinstalled one of the monitors into the cabinet, put the repaired board back in place and tried to play a game. I didn’t get very far. I couldn’t coin it up to start a game. The super-detailed manual offered this schematic for the area in question:


With a little poking and prodding i began to suspect that the flip/flop at C7 wasn’t flipping or flopping, so I replaced it. (At this point I will omit an embarrassing side track I went down first where I thought the problem was with the start button on the front of the game and in testing it managed to bust a connector and had to make a special trip of shame to the parts store just to get it working again.)


So yeah, let’s pretend everything went smoothly and I easily found and replaced the bad chip. I put the repaired board back in the cabinet, coined up the game, and something new happened. I could start the game and the timer began count down but the throttle still didn’t work. Even stranger, when I shifted into third gear the whole game would groan and dim, as if I just created a short circuit. Clearly there was more work to be done.

Gran Trak History Part 3

One of the things that intrigues me about this game is that it has three “hybrid” chips. As far as I know, the first to appear in a video game. They are called hybrid because they contain a mix of digital and analog parts. You can see them below, two square and one round:


But why? Why did Atari go out of their way to make their own chips for this machine? There are several possibilities:

One possibility is that hybrid chips were the only way to accomplish what the designers were trying to do, which, in this case, is calculate the acceleration of the car over time in various gears. I don’t think this is why they made them because newer versions of the board replace the hybrid chips with small printed circuit boards that use normal chips and other discrete components. They are about the same size and perform the same function as the hybrid chips. They look like this:


Another possibility is that the chips were made to make it difficult to pirate the machine. When Atari’s game Pong was released and became an overnight success it was very quickly copied by other companies and there are dozens of Pong clones floating around. If a game used a chip that belonged only to Atari and the contents of that chip were secret, it would be much more difficult for someone to create a clone of the board. Notice in the schematics below that the three hybrid chips (marked 8103, 8099, and 8098) are treated as black boxes we can’t see inside:


The manual says “This circuit uses three custom chips which have been designed specifically for Gran Trak 10 and are available only through Atari Inc.”

To further support the case that these chips were originally designed as “security” chips, check out this picture from the Gran Trak 10 of collector Matt Griffin:


In his case he has the E revision board, same as mine and the earliest we have found so far in the wild, but one of his chips was replaced with a board. Someone really didn’t want us to see what’s going on in there so they glued a block of black plastic on top. A true black box! Here’s what the underside looks like, again courtesy of Matt Griffin:


So the case for these being security chips is pretty good. In my interview with Larry Emmons, the designer of the chips, he says as much:

“Oh, I think it was the idea that it would be harder for people to copy. I think that was the main motivation. Whether that was a valid concern or not, I don’t know. I’m pretty sure that’s why it was done. There was a lot of extra work and cost to do it that way” – Larry Emmons

But when I asked Steve Mayer if that’s why they did it he said:

“It was a bit of a consideration but what was really driving it is with each game we tried improving Atari’s technology. We got pretty far on the digital side. Larry Emmons was a great analog engineer and he wanted to see whether he could do an analog chip because, if he was able to do it, it could be used in a wide variety of games and would eventually be a lot cheaper than having to use all those op-amps and all that. You know, we could have done it all digitally, but Larry wanted a chance to see what it would be like to design an all analog circuit and he was a superb engineer and if it worked it would put a new technology into the basket of things we could do.”

So there you have it. Like true engineers, they did it because they could.

Really making it go

I put the whole discourse on the hybrid chips here in the story because I suspected one of those chips was the next thing causing my problems. If you look at the schematic above, third gear from the gear shift and the throttle (marked as “Gas”) both connect to the same chip: hybrid chip 8099. Seems like a good theory, but if that chip was broken, where could I possibly get another one?

Just kidding. As it turns out, I had more than enough. As I wrote in my last story, I had started to collect old (pre-1976) game circuit boards on eBay. Months before Dave dropped his game off I had already bought a set of two boards marked GT10 and two more boards marked “Formula K” (the Kee Games version of the same game). Then Dave’s game came with a board and, because he had parted-out another GT10, there was one more board, for a total of six all together.

To make things even easier, the two big square custom chips are in sockets so you can just unplug them. I pulled one off another board, swapped it with one on this board, plugged it all back in and this time… it worked!

Now I could race my car around the track. Wind in my hair. Engine roaring. Wait a minute, there was no engine roaring. In fact there was no sound at all. Sound. Why do I always have trouble with the sound??

A Series of Curious Coincidences

Before I could dive into the sound problems I had to prepare my talk for Portland Retro Gaming Expo (PRGE). I planned to mostly speak about Fixing Computer Space and Fixing Color Gotcha but I thought I’d stick a bit in at the end about Gran Trak 10. Up to this point I hadn’t had time to look into the ROM (short for Read Only Memory) chip. I figured if I’m going to talk about GT10 I better know something about the ROM since GT10 is best known as the first game ever to use a ROM. But the more I looked online the more I found absolutely nothing. Understand that there are thousands (tens of thousands?) of ROM data dumps online for virtually every arcade game ever made. Could it really be possible that no one had ever dumped the first one?

Just then I got a text from my old friend Chris Taylor asking me out to lunch. I hadn’t seen him in ages, so of course I said yes. But then I remembered that Chris dabbles in electronics so:


We didn’t fry it. But we didn’t succeed in dumping it either. The chip said 74186. It looks like this:


But what’s a 74186? Some sources online seemed to indicate that there was a 64×8 bit ROM manufactured with that number. That’s a pretty tiny ROM but this was the first game with a ROM so maybe it makes sense? But the more I thought about it the more that didn’t seem right. How could you fit the layout for the track plus the bitmaps of the car at different angles all in 64 bytes? I decided to cheat and ask Atari chief engineer Al Alcorn.

His response was interesting:

“The board used a ROM chip that had the images of the cars at various rotations and it was a custom part.  I chose the part number to be SN74816 which was a TTL part that was the same package as my custom part.  When the copiers plugged in the standard TTL part it burnt out.  We learned who was copying our boards because they would call our customer service and complain.” – Al Alcorn

Funny! He also told me the ROM was manufactured by a company called “Electronic Arrays” which only lasted a few years before going out of business. So this is a special ROM. No wonder no one had dumped it before, or so I thought as I drove down to Portland to give my talk.

PRGE and Teeray

In Portland I ran into my new friend Steve Golson. Earlier in the year, at the game developers conference, I had heard his incredible talk about how a group of MIT dropouts created MS Pac Man but I didn’t get a chance to speak with him. Then we both found ourselves presenting at an event called ReplayFX in Pittsburgh and got to know each other a little better.

Steve sat through my talk in Portland and afterward offered to help me with the ROM and was also very interested in looking at the hybrid chips. We agreed to collaborate and went our separate ways. When I got home I mailed one of my extra ROMs to Steve, but he never had a chance to try to dump it because fate intervened once again.

Out of the blue I got an email from a Tim (Teeray) Giddens. He had been reading  Fixing Color Gotcha and had noticed that at the top of the article I used a schematic image that hadn’t been seen before. He explained that the image must have come from this manual:


He was trying to find a copy so that he could scan it and make it available to all game collectors online. A noble goal! Unfortunately I had to explain that I didn’t have the manual and that I had taken the image from a Facebook post by well known collector Andrew Welburn.

Tim went on to share some interesting information about Color Gotcha. At the end of his email he said that he had a smaller version of the manual he was looking for but his version only covered Gran Trak 10. When he mentioned Gran Trak, of course I told him that I was working on that game. He said that he was too, along with another friend, and that they had dumped the ROM!

What followed was a series of emails with amazing things attached. The first images from the first ROM in video game history! Not only had Tim dumped the ROM and formatted it so the contents could be easily viewed, but he had also figured out the custom codes embedded in the track data which mark the start/finish line, checkpoints and oil slicks. The first page he sent me looked like this:


That’s the track! And a little later on in the ROM we find the rotations of the car:


What are the chances that the one guy in the world who has the completely obscure thing I’m looking for would reach out to me right at the time I’m looking for it? And it only got better. Not only did he have a ROM dump but he was in the process of documenting the hybrid chips. He started to send me schematics he had drawn based on the daughter boards:


Fortunately the conversation wasn’t all one way. I had something Tim wanted also and pretty soon we had exchanged dozens of emails, photographs, and even a few packages through the mail. I had a (nearly) working GT10 and I had six boards for the game across four major revisions of the board from E through K. Most of those boards had ROMs on them and one of the boards had a really strange two ROM adapter stuck into the ROM socket. Tim wondered if these ROMs could hold the key to a mystery that he, and it turns out, Andrew Welburn, had been chasing for a long time. But first, let’s fix the sound.

Fixing the Sound Part 1

The sounds on GT10 are really great. It has three sounds in all: A crash, a screech, and a beautiful engine sound that revs up as you accelerate. Steve Mayer explains how they made the screech:

“We wanted the sound of the screeching brakes. Tektronix had just brought out a new measuring device that could do a Fast Fourier transform so we could then bring in a sound recording of a car screeching and we could look at the spectrum and we realized it was a single frequency that was FM modulated back and forth through random noise and that’s how the screech sound worked. I knew we got the sound right because I was working on the sound in the lab one Saturday and my dog was there by me and I tried the screech sound and the dog ran!” – Steve Mayer

On my GT 10 there was nothing coming out of the speaker. I mean nothing. Well, let’s start at the speaker and work our way back. The speaker is fine. It’s connected to the board. The first thing on the board is the audio amplifier:


It clearly should have 18 volts coming into pin 14 and it has… zero volts. Pin 14 was connected to three diodes that had been creatively soldered together end to end:


It didn’t take long to figure out that one of those diodes had gone bad. I replaced it and was rewarded with some hisses from the speaker. Not the sounds I wanted, but it was a start.

Next stop was to look at the engine sound schematic:


I checked the test points and nothing looked right. As much as I hated to blame the obvious 566 frequency generator chips, I couldn’t see anything else that could be wrong. Vetco doesn’t carry those chips so I’d have to order them online. In the meantime I pulled one off one of my other boards and put it in place:


That gave me some engine sounds but I would have to wait for my other parts to arrive and replace the other two 566s to get the full experience. But there was another problem: it made engine sounds even between games! The transistor Q3 in the schematic above was pretty clearly there to stop that from happening so I replaced it and was treated with the silence I so richly deserved. Now if only the screech sound was working…

Chasing Roms

Once I saw Tim’s ROM dump I let Steve Golson know he wouldn’t have to dump mine and so he mailed me back my chip. I had noticed that Andrew Welburn was looking for a GT10 ROM on his website so I sent him an email offering my extra. His response came as kind of a shock. He said he didn’t think I had a ROM from Gran Trak 10. Wait, what?

To understand his reasoning I have to explain some things I’ve only hinted at earlier in this article. First of all you need to understand that each of these roms hold not just one track, but two. Why? Because (to make a long story somewhat shorter) at this time Atari operated as two “separate” companies. The other company was called Kee Games and was run by Nolan Bushnell’s neighbor Joe Keenan. At that time, the distributors of arcade games wanted exclusive partnerships with their suppliers. But Nolan wanted to be able to sell more games by selling to more than one distributor, so he enlisted his neighbor to make a “competitor”. Atari would release a game and then, soon after, their arch-enemy Kee Games would copy it with slightly different features and release it to their distributor. Of course they were cooperating behind the scenes the whole time. The Kee Games copy of Gran Trak 10 was called Formula K and it used the same rom as GT10 but with one wire switched on the PCB to show a different track.


The second thing you need to understand is that GT10 is famous for almost bankrupting Atari. The game was popular and sold well, but that was part of the problem. It was so expensive to make that Atari was losing money with every sale. This caused a second, unexpected problem with their hybrid chip supplier National Semiconductor, as Al Alcorn explains in an email to me:

“To make matters even worse after delivering a limited number of parts they decided our deteriorating financial condition warranted putting us on credit hold and thus preventing us from shipping and making sales that would pay our bills” – Al Alcorn

So those fancy hybrid chips the guys from Cyan had developed were no longer readily available. Al responded by designing a set of replacement boards that would function the same as the hybrid chips. His team also designed a new version of the game that was cheaper to produce called “Trak 10”. It looks like this:

There were also two player versions produced with the Atari version called “Gran Trak 20” and the Kee Games version “Twin Racer”.

Now that you understand all that, I can tell you that what Andrew said in his email to me was that he thought I had a “Trak 10” rom, not a “Gran Trak 10” rom. Could Tim and I have been working with the wrong rom all this time? I’ll explain the evidence for Andrew’s argument in a minute, but first, let’s fix some more stuff.

Fixing Sound Part 2

So my engine was roaring but the game wasn’t screeching when I pushed on the brake or hit an oil slick (did I mention the game has oil slicks? how cool is that?) The manual had a handy note on the bottom of the schematic for the screech and crash sound. It suggests making something called a noise probe. This lets you poke around and hear sounds through a speaker rather than just looking at a waveform on an oscilloscope and wondering what it sounds like.


As instructed, I built my sound probe, which is basically just a wire attached at one end to the audio output, and started poking around. As usual when it comes to me and sound, nothing was going on. I spent time staring at all the capacitors and resistors and then did what I always do, I replaced the big chip in the middle. In this case the chip in question is called the rc4136 and is just four 741 op-amps in one package.

As usual I had to order the part, put it in using my flawless soldering skills, and everything worked the first time (as far as you know).

Now let’s get back to the story of the maybe missing mystery rom…

The Maybe Missing Mystery ROM

Okay, so if you’ll recall, one of the world experts in video games of this era, Andrew Welburn, was telling Tim and I that we didn’t really have the first ROM ever made. That there was an earlier one, and he was hoping to find it (maybe before us…).

The main ROMs we had were labeled 74186 and contained these two tracks:

The Gran Trak 10 track



The Formula K track


But Andrew pointed out that the advertising flyers for the games, presumably released at the time the games were first being sold, show two entirely different tracks:

gt10 flyer



He went on to make some additional arguments based on schematics for a very early revision of the board (revision B) that only appear in the manual “Atari Computer Games Operators Handbook”. The very manual that Tim wanted to get his hands on in the first place.

My initial reaction was that the advertising flyers must have been made based on some prerelease version of the game and that all the shipping versions used the 74186 ROM, but really that was just a guess.

As Tim and I investigated further we found some hints that Andrew might be right. For example the parts list in the manual says the ROM is a 74186:


But when we looked closely at the “computer board component layout” page it shows this image of the rom:


What’s this? 74181? Could this be the mystery ROM? 74181 is before 74186… Tim also noticed that the ROM used in the next game Atari/Kee released, Tank, is labeled 74182. Interesting…

After exchanging a few more emails, Andrew sent us scans of the revision B board from his manual. Here’s part of the main board:


Let’s zoom into that rom and flip it over for a closer look:


Yup, that’s 74181 all right. These schematics have a date:


It’s kind of hard to read but it says 11/27/73, so that’s well before the release in March of 1974. The schematics also refer to this as a prototype or proto:


So does that mean that Andy is right and there should be a missing 74181 ROM chip out there somewhere or that I am right and these other tracks were only used in prototypes, not the actual shipping game?

I checked all the other ROMs I had. Other than a crazy two ROM board, they were all marked 74186 and had the same two tracks as Tim had originally found. Tim helped me hook up the two ROM board which looks like this:

IMG_5104 (005)

And we found that it had the Formula K track and a second track I hadn’t seen before:


Unfortunately it didn’t match either of the tracks we were looking for from the flyers. I speculated that it might be for Twin Racer, the Kee Games two player version of this game. Sure enough, Tim quickly found proof that was correct:

110033001 (003)

It was around this time that I started interviewing the creators of the game: Steve Mayer, Ron Milner, and Larry Emmons. In each case, after hearing their versions of the creation story, I told them about this situation and asked them if they had an explanation for what we were seeing, but none of them were sure. They had used a ROM simulator when they were making the game, not an actual ROM. Programmable ROMs had not yet been invented so to make a ROM involved sending the data you wanted on the ROM off to the chip manufacturer and waiting weeks if not longer to get a chip. With a ROM simulator, which it sounds like was just a big box full of RAM, they could modify the tracks and other data anytime they wanted. When the game was ready they just passed it over to the main Atari office to put into production (and to create advertising flyers). They had no involvement in that.

Larry Emmons did send me a picture of his kids playing the early prototype of the game:

Track 10 prototype 1973001

If you look very closely you can just make out that the image on the screen matches the image on the flyer. I think this proves that the flyer was made using the prototype tracks but it says nothing about whether the prototype tracks ever made it out into the real world (presumably on a chip labeled 74181).

Searching for Bob

Well, if I can’t find the first ROM, can I at least find the person who created the tracks? I mean, if you think about it, all the games before this were done strictly in hardware. The objects on the screen were mostly simple rectangles (the ball and paddle in PONG for example). Where there were things that looked like sprites they were created from diodes soldered directly onto the printed circuit board. But with Gran Trak 10, for the first time, a person could draw a picture of a car and a track and have it show on the screen. Wouldn’t the first person who did that be the first artist in video game history?

So who is this mystery artist? I asked Steve Mayer and he said he thought it might be a guy named Lanny Netz. Ron Milner gave me Lanny’s phone number so I called him up. We had a quick conversation during which he assured me that he didn’t do it. He thought Larry Emmons might know and gave me his number. I interviewed Larry and he said he thought it might have been a guy named Bob Walker. I checked back with Steve and Ron but they didn’t know how to find Bob.

I tried googling for “Bob Walker Atari”, but all I kept finding was some lady named Atari who really likes cats. I asked Marty Goldberg, who knows everything about Atari. Nothing. I asked Jon Hardie who runs the National Video Game Museum. Nothing. Oh well, I better finish fixing this thing.

Fixing the cabinet

Let’s just clear one thing up right here. I’m not that big on restoring cabinets. It’s just not as interesting to me as fixing the electronics. I don’t particularly excel at woodworking, and who likes cleaning? But there’s a basic level of restoration that needs to be done to make a game functional and to make it an attractive part of my collection.

A great tip I picked up from a podcast was to use a product called the “Magic Eraser”. I don’t know what this stuff is (melamine?) but whatever it is it really cleans up these old machines.


I had to replace a broken ring that holds the gear shift. I was able to get a new old stock part from John’s Jukes in Canada. He provides a great service to the hobby by stocking these old parts. I removed the Kee Games steering wheel someone had put on and replaced it with a proper Atari wheel. I fixed the brake pedal. I repaired the lights behind the marquee. But most of the work was in trying to fix up the side art that had been badly damaged in arcades over the years. Here’s what it looked like before I started:


I tried to fix it with a black sharpie, but then switched to a furniture pen and that worked even better:


Here’s what that same section looks like after touch-up:


Fixing scratches in the orange/red checkerboard was much trickier. I tried a red sharpie but the color was way off. Finally I resorted to buying a collection of “adult coloring book” pens (I hope that doesn’t mean what it sounds like it means) from Amazon:


Although they were not as easy to use as felt tip pens, at least I was able to find a color that was a pretty good match.

The game still has some dings and blemishes as you would expect from a 40+ year old game, but I’m still pretty happy with the final result:


Now here’s a short video of the finished game in action:

Finding an ending

I tried really hard to find a happy ending for this story. I had a completely working Gran Trak 10 for my collection, which is great, but could I find the missing mystery ROM? No. Could I find Bob Walker? Again, so far, no.

At this point, all I can hope for is that a collector will read this, look inside his machine, and find a ROM labeled 74181. Then again, maybe it doesn’t exist at all. Maybe we already have the first ROM ever and Tim has already documented it. (74181 Found! See: Finding the First Videogame ROM).

Maybe Bob Walker will rise from obscurity to take his rightful place as the first artist in video game history. Or maybe he will deny any involvement, just like Lanny Netz.

Probably none of these things will happen. But even so, we can still appreciate Gran Trak 10 for what it is: The first video game to use a ROM. The first with a high resolution display. The first with custom, hybrid security chips. And on and on.

In this sense, Gran Trak 10, laid the groundwork for virtually every arcade game to follow. Its creators, Steve Mayer, Ron Milner, and Larry Emmons, deserve to be remembered for their enormous contributions to video game history.  Hopefully this story will help in that regard.

(special thanks to everyone who helped with this project over the last nine months including: David Oliver, Tim Giddens, Andrew Welburn, Al Alcorn, Steve Mayer, Ron Milner, Larry Emmons, Lanny Netz, Matt Griffin, Marty Goldberg, Van Burnham, Chris Taylor, and Steve Golson)




25 thoughts on “Fixing Gran Trak 10

  1. Ed,
    This is a great story. Appreciate that depth you go in trying to find the origins of the electronic gaming world. Having lived in the Bay Area in the mid-70s we got one of the first pong consoles though some friends who worked on the games. Really cool stuff. Thanks for sharing as the history of these early games needs to be documented before it is too late.

    Liked by 1 person

  2. The track shown in the Gran Trak 10 flyer and in Larry Emmons’ photo is one of the tracks in LeMans (1976) – 6th track to be specific (“Daytona”). Btw, LeMans pcbs are compatible with Gran Trak 10 pcbs. The only difference is the gear stick (Gran Trak uses 3 gears and a reverse gear whereas LeMans uses 4 gears.)


    1. This is close but not quite true. You are right that the flyer track must have been used to create the 6th track in LeMans but there are subtle differences, for example on the middle left hand side and also on the spike sticking down from the top. I can send you pictures if you need them.


      1. I have some pictures:
        You’re right, it’s not the exact (pixel for pixel) track, but It’s clear the designer(s) of LeMans used the same track and made 3 subtle differences in how you play it. An obstacle in the middle of the road doesn’t make it a different road but rather how you drive the road differently 🙂


  3. Great work, Ed. It’s awesome that we have someone with the engineering knowledge looking at these old games, and I was especially looking forward to this one because I really love the story of Cyan.

    I have looked through some old court documents relating to Cyan on their work with the microprocessor pinball games. While that gives no direct link to Gran Trak 10, there are a couple of Cyan names that maybe could give you a lead on finding the enigmatic Bob Walker.


    1. I also noticed on the proto board, it has the two hybrid square chips but the circular chip is marked as a completely different number. They also appear to be in a different location. Originally it was supposed to be one chip, sourced to National Semiconductor (according to Alcorn), but they had to split it up. Am I seeing that right? It’s at the top of the board.


      1. Yes, there are three hybrid chips. Two square and one round. I’m not sure why the packages are different and I also wonder why the square ones are socketed and the round one is soldered directly to the board. Other than those differences, they are all treated as black boxes on the schematic in the manual and it says you have to order replacements directly from Atari.


  4. Fantastic look at a game whose origin has remained largely shrouded in mystery until now despite its importance. I am curious about Formula K. In your research and board collecting have you been able to tell if Kee fixed the hybrid chip situation in the same way that Atari did, and/or whether it was fixed first at Atari or Kee? The reason I ask is there are two stories floating around about the redesign. Al Alcorn, in his Computer History Museum oral history and elsewhere, says he did the whole redesign himself after being brought back from a leave of absence. Meanwhile, Steven Kent in his Ultimate History of Video Games states Steve Bristow developed a “piggyback” board to replace the hybrid chips and that Atari also adopted his solution. This info (found on page 95) does not come from a direct quote, but Kent did interview Bristow. The stories do not necessarily contradict each other, since Alcorn could have simply incorporated the Bristow fix as part of his own redesign.

    Looking through Cash Box and Vending Times, Atari announced in the March 23rd Cash Box and the April issue of Vending Times that they had started shipping Gran Trak in late March. Cash Box calls these shipments “samples,” and Vending Times calls them “early orders.” The first ad for Formula K appears in Vending Times in the May issue. On May 18th, Formula K starts getting mentioned in the Cash Box “Round the Route” column that details regional happenings in the coin-op world. Cash Box never runs a formal release announcement for Formula K, but Vending Times does in its June issue. Taken together, these articles indicate the game was probably released in early May, though it could have been late April as well. Meanwhile, on May 4th Cash Box announces that the first Gran Trak 10 units arrived at a distributor the week before.

    The gap between the two Gran Trak announcements implies that Atari first tried to bring it to market in March and were forced to delay the introduction, most likely due to the National Semiconductor issue. It then made a return in late April, which is around the same time Formula K started shipping from Kee. This may indicate Kee only ever shipped a “fixed” version of the game.


    1. This is great analysis and interesting questions which were too detailed to go into in my story. Let me try to answer your questions as best I can:

      1. Who designed the hybrid chip replacement daughter boards? I don’t know for sure. I didn’t know about the Steve Bristow comment. I asked Al Alcorn about this last October and in an email he told me “I personally re-did the board with discrete components which took less board space than the three custom hybrids.” So he claims he did it. But he also claims they are smaller than the hybrids which is debatable. Between Andrew, Tim Giddens, and myself, we have looked at dozens of boards. All of them either have 3 hybrids, a mix of hybrids and daughter boards, or all daughter boards. We have never seen any other version of Gran Trak, Formula K, Trak 10, Gran Trak 20, or Twin Racer that integrates the components directly on the board. I personally don’t believe that happened until LeMans and maybe that’s where some of this confusion is coming from.

      2. When did it ship? This Document lists Gran Trak 10 in March ’74 and Formula K in April of ’74. I also like to use Cash Box as a way to check these dates and I think you bring up some valid points that it might be later. Just to add to the confusion a bit I will add another quote from my correspondence with Al Alcorn. He said: “Gran Trak with hybrids are extremely rare. By my recollection they were in the double digits.” So this is an interesting and confusing statement. What I believe he is saying is that they may have shipped a few dozen units, then ran into problems, did a redesign of some kind, and then started shipping again. This could match what you are saying about dates (the gap). It might even mean that these few dozen units used the 74181 ROM that we would love to find if it exists. What it for sure doesn’t mean is what it literally says, because “Gran Trak with hybrids” are not “extremely rare”. Every revision E board I’ve seen has at least some hybrids and most have all hybrids. Even many of the later board revisions have hybrids as well.

      3. So what is a Formula K board anyway? We (Andrew, Tim and I) believe the Formula K boards are identical to the Gran Trak boards except in two ways: They have an additional socket on the board that connects to a “lap timer” that was only available on Formula K. Tim and Andrew are working on documenting that. A Formula K board should also have a certain pin tied to ground (or +5, can’t remember which off the top of my head) which selects the Formula K track in the ROM. Of the 6 boards I have, none have the socket so I don’t think I have any actual Formula K boards. Andrew has at least one, maybe more. Tim knows this part better than I do.

      4. So to answer your question, did Kee only ever ship a “fixed” version of the game? I say the answer is no. I’m looking at a picture of a PCB Andrew sent me of what he says is a board out of his Formula K. It has the extra socket I mentioned above. It’s a revision E board which is the same revision we see in the early Gran Trak 10s (we’ve never found a revision earlier than E). It, interestingly, has 2 hybrid chips and one daughter board.

      Phew. You can see why I leave this stuff out of the story for the most part. It’s long enough already! What I’m learning from all this is how hard it is to get the history behind these things exactly right, even with access to the people who made them.


      1. Thanks for the additional info. That Formula K info does beg the question of whether that daughter board could somehow be related to Bristow’s alleged “piggyback” fix, but it hardly seems much of a fix if two of the hybrid chips are still present.


  5. I enjoyed every word of this — thanks.

    Marty Goldberg’s book mentions that Steve Mayer hired “a tech named Bob Walker (son of an Arvin employee)” after he and Larry Emmons were brought on to work on game circuits for Syzygy/Atari (while Larry hired Lanny Netz from Arvin, too).

    So as not to post personal information here… I think that (if you wanted) you might get closer to locating the enigmatic Robert Walker by searching for [“Arvin Systems” Walker] and/or [“Arvin Automation” Walker].

    On a related note, I believe in the “Stella at 20” documentary Ron Milner mentions that it was Bob Walker who wired the first Stella wirewrap board for Cyan Engineering, too.

    Liked by 1 person

  6. What a great story. Thank you so much for documenting a really important part of videogame history. I really hope you find Bob Walker so we can honor him some day.


  7. you had could save time, because we in Austria did allready dump that rom in April 2016
    All the Rom pinouts and functions of this obscure Rom was post on a german Videogame forum then.

    Its interesting that we debug the same game in April 2016 🙂

    I contacted Bushnell but got of course no response. I was in contact with a mame developer too..
    it starts because I buyed a unknown pcb from Ebay in March 16. It was an Gran Trak 20

    Congrats for make this wunderful Blog with all relevant datas condensed togheter. Thank you for that.

    Kind regards

    Liked by 1 person

    1. Thanks Markus. I don’t read German so even if I had found that forum page I probably wouldn’t have known what you guys were up to. Congrats and I hope you continue to contribute to uncovering the history of these important games.


      1. Yes we are reversing always old stuff… thanks for the audio schematics of the security chips. That was new to me. great work – when the right people come togheter 😉


  8. btw. do you know why you got 3 IC socket for the ram ?
    The roms a and b you only need if you haven´t a TI Mask Rom. then you can populate a and b with signetics 2580 (NiCr) proms. every one of them has an 4 bit databus.Only the TI maskrom has an 8bit databus.
    So this is an option if TI is running out of maskroms ….

    the same I verified on my Grantrak 20


    1. It looks like a socket in between those two roms but it’s really just the top of some header pins that project below so it can be plugged into the single rom socket on the GT10 board.


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