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# 2025-08-08 - Robot Odyssey, Escape From Robotropolis | |
My high school German class used learning software in the obsolete | |
Apple II lab. Normally i finished my work early and had time on my | |
hands. I explored boxes of old software on the counter, and i fondly | |
recall playing Robot Odyssey, a puzzle game. I played it on a green | |
CRT. | |
Robot Odyssey (Wikipedia) | |
Recently i found appler, an Apple II emulator for the IBM XT/AT and | |
decided to give it a spin. It compares favorably to the other MS-DOS | |
Apple II emulation software (appleuni, capple, applepc, sim2e, and | |
xgs) on ftp.apple.asimov.net. | |
appler Apple II emulator for MS-DOS with TASM source code | |
ftp.apple.asimov.net | |
I went ahead and packaged Robot Odyssey with appler and tested it in | |
DOSBox and in SvarDOS on real hardware. It is more colorful than the | |
IBM PC port and it works great! | |
Robot Odyssey in Appler (ro-apple.zip) | |
Alan Kay said it would be impossible to create this game on early | |
1980's hardware. Never tell a hacker that something is impossible! | |
The game is "way out there" because you can design chips in game. | |
The novelization of this game contains prescient social commentary. | |
See articles below for more details. | |
# 2025-Apr-10 - A Robot Odyssey Odyssey by Sean Duggan | |
Decades ago, I experienced Robot Odyssey on my family's TRS-80 Color | |
Computer, and it was awesome. The basic concept of the game was that | |
your character is preparing for bed when they fall through the floor | |
of their room into the underground city of Robotropolis, where they | |
have to program three robots to find their way home. | |
Opening Animation | |
## The Game | |
And how do you program them? Was it BASIC? C++? Python? Some bespoke | |
scripting language? Nope, you program them with logic gates. Every | |
robot came with four bumpers and four thrusters, corresponding to the | |
four cardinal directions, as well as a grabber and an antenna which | |
come with an input and an output. You wire them together with OR | |
gates, AND gates, XOR gates, and FlipFlop circuits (and nodes, but | |
they're essentially a convenience to split the signal). And, with | |
those, you solve everything from simple puzzles involving going right | |
until you hit a wall, and then going back again, to navigating a | |
minefield by communicating via the antenna (which is entirely binary, | |
so you have to figure out how to communicate via that!), to hitting a | |
series of 8 switches in a very specific order within a short amount | |
of time. The first level could be completed with the robots as wired, | |
just putting them in place and watching them run. The second level | |
required fairly basic logic, around the level you'd probably | |
understand in grade school. Third level and above... you're starting | |
to get into concepts that are so complicated that you're getting into | |
undergraduate levels of problem-solving, requiring you to get the | |
robots to count, to store and retrieve data, to navigate mazes... and | |
all of this with logic gates. | |
Honestly, one starts to understand why, despite the game technically | |
being titled Robot Odyssey Part 1: Escape from Robotropolis, we never | |
got a Part 2. As a child, I made it to the third level, and my older | |
brother who went into software engineering made it past the fourth | |
level, but frankly, the late levels were getting into college-level | |
thinking and beyond, with them dumbing down later games that used the | |
engine, like Gertrude's Secrets. But still, making my way through the | |
game as a child was, I think, one of the reasons I became a software | |
engineer myself. It requires a degree of creativity and logical | |
thinking that I think too few children are pushed toward these days. | |
Which leads me into the reason I wrote this article. | |
## The Book | |
Yes, the game got a novelization, Robot Odyssey I: | |
Escape from Robotropolis and, much like the game it was based off of, | |
it looks like a book for children, but is really written to a much | |
higher level. | |
Book Cover | |
The basic plot is simple. Homer is a child in a future where robots | |
are a routine part of life. One of his childhood toys is a robot | |
named Denby, that he considers to be his friend, up until it goes | |
missing. He meets a bright boy his age named Les, and they follow a | |
shared vision, to create a new Denby, made in human form, and as | |
intelligent as they can make him. Hiding their activities from their | |
parents, they learn enough to put him together and activate him... | |
only for tragedy to strike. Upon activating Denby, a shock knocks | |
Homer unconscious and when he awakens four days later, he's told that | |
Les was killed by the shock, and Denby had melted down. Homer, of | |
course, is despondent, and further finds that himself discontent with | |
current society, where robots are taking over every aspect of human | |
existence, and children are growing increasingly ignorant as they | |
stop learning things that robots can do for them. | |
> But what was it that people did best? | |
> | |
> No one was quite sure. Some people argued that humans were more | |
> creative than machines, so they should let machines do the | |
> "donkey thinking" and concentrate instead on creative | |
> thinking--things like making music and sculpting statues. Other | |
> people said that since work was being automated anyway, people | |
> would soon have more leisure time. Instead of thinking about work | |
> they should be thinking about having fun. "Having fun can be a | |
> uniquely creative, uniquely human, activity," said one expert, | |
> quoted in Technology Times magazine. | |
> | |
> Teachers eventually bowed under all this pressure, and machines | |
> took over the classroom, just as they had taken over offices, | |
> homes, and factories. Teachers rationalized this takeover by | |
> telling each other that they would let the machines do only the | |
> low-level mechanical work like looking up names of presidents, or | |
> solving algebra problems, or conducting a chemistry experiment. | |
> This would enable them to teach students the higher-level, | |
> conceptual subjects that human minds were supposed to be good for. | |
> | |
> But they didn't. | |
> | |
> That's because most teachers were not prepared to teach | |
> higher-level thinking skills to their students. They hadn't learned | |
> them when they were in school, and they didn't have the time to | |
> learn them now. Besides, for the first time in years, they were | |
> getting a break. Smart desks, intelligent tools, and | |
> teaching-assistant robots were doing most of the teaching, grading, | |
> and record-keeping. Kids' test scores were soaring (since the | |
> machines helped them answer most of the questions). So why put the | |
> extra effort in just to teach abstract concepts? | |
Ouch... that kind of sums up what so many experts are saying is | |
happening to the current generation of kids, not to mention the dire | |
warnings of what will happen when the expert systems start breaking | |
down, because the generation that would have learned how to fix them | |
by doing the little things won't exist, because the expert systems | |
have been doing those little things. Homer's odyssey (Oh... I see | |
what they did there) also touches on the dangers of ubiquitous | |
surveillance and the dissatisfaction when your job comes down to | |
plugging the diagnostic computer into a system and following its | |
instructions, leading to Homer using drugs (well, neurostimulation) | |
and escapist games of sex and violence to escape this soul-sucking | |
existence. Really... this book was terribly prescient. | |
## Robotropolis | |
You might ask what this has to do with the game now... well, halfway | |
into the book, the robots abduct Homer to Robotropolis, and explain | |
that he is a danger to their plan of world domination because he has | |
the temerity to think for himself, rather than to follow the | |
instruction of the robots. Oh, and robots are actually the minions of | |
ancient aliens who want to avoid humanity from growing too strong and | |
challenging them, with them having put a lot of effort into getting | |
humanity to fear constructing machine intelligence in their own image | |
and thereby realizing their own greatness. Yup, tales of Prometheus, | |
Talos, the Prague Golem, Frankenstein, and R.U.R. are all the results | |
of robots trying to discourage human creativity. They don't quite | |
understand how an aberration like Homer came about, so they're | |
testing him by tasking him to escape Robotropolis within 24 hours | |
while they monitor him so that they can understand where their | |
protocols went wrong. And thus, the narrative speed-runs the game. | |
It's actually pretty amazing just how true to the game the book is... | |
I recognized level after level despite that they inject actual plot | |
into bits that were frankly probably just decoration, like the | |
disassembled bots on one level (noted to be torture of robots who | |
rebelled against the central order) or aliens on another. Homer | |
experiences genuine peril and distress as he escapes death by the | |
skin of his teeth, and even wrestles with the Teletransportation | |
Paradox (sometimes discussed as the Transporter Problem) when he not | |
only realizes that taking the teleportation device between levels is | |
technically dying and having a new him created at the other side, but | |
also starts to realize from some comments by his Mission Control (a | |
voice contacts him early on, and cryptically explains aspects of the | |
world, and how to solve puzzles) that he has probably died on parts | |
of the level, only for the transporter to spit out a new copy of him | |
who is then better informed of the perils before him. There are bits | |
of the levels where puzzles are mixed up, but many of them are | |
extremely recognizable, to the point where the novel could act as a | |
hint book to the game. | |
I will admit that I was expecting a slightly different twist than the | |
one that the book ends on, but suffice to say that not all of what | |
happened in Homer's childhood is exactly as he remembered it, and | |
there's a reason behind his being tested like this. It's not much of | |
a spoiler that he escapes Robotropolis, and vows to come back and | |
free the enslaved in the underground city in Robot Odyssey II, were | |
the sequel game and book ever written. At the end of the book, | |
there's hope for humanity, but I can't help but feel that Homer has | |
quite the trek still ahead of him. And maybe, just maybe, we can | |
learn a bit from how dismal his future was, and how we can fix that | |
in our society today. | |
## Start Escaping Robotropolis Now | |
You've made it this far into the article? Congratulations! You've | |
earned the earned the right to challenge Robotropolis yourself! | |
There's an online copy of the game. Or, if you want an expanded | |
experience of the game (and the chance to expand it yourself), Thomas | |
Foote wrote a Java implementation of the original game (complete with | |
a super-secret sixth level with even harder puzzles, as well as | |
improvements in the interface and the Innovation Lab!). | |
Robot Odyssey Rewired | |
DroidQuest | |
Explore! Learn something new! Share the frustration of incredibly | |
difficult puzzles in a game marked as 10 and up! | |
And, above all, never stop thinking and creating... | |
Splash Screen | |
From: https://medium.com/@sean.duggan/a-robot-odyssey-odyssey-34707092639d | |
# Other Chips In Robot Odyssey | |
## Stereo Recorder chip | |
Here's the schematics of the Stereo Recorder: | |
Stereo Recorder schematics | |
Each nested chip is a Mono Recorder. Here's how a Mono Recorder is | |
done: | |
Nested chip: Mono Recorder - schematics | |
It's actually a circle of OR gates. The "recording" is stored in the | |
intermediate subnets. | |
Note that the above version is not binary-compatible with the | |
original Stereo Recorder, that is, it does not produce the same | |
savefile. The following version is binary-compatible, but it's a bit | |
uglier: | |
Nested Mono Recorder, binary-compatible | |
The total chip length is 516 bytes, which exceeds two sectors by just | |
4 bytes. It's possible to reduce the length up to a point where four | |
chips fit, more than doubling the total tape length. | |
The idea behind this is to use inverters instead of OR gates. The | |
following section shows a design. | |
## Enhanced Stereo Recorder | |
Here's a design using the above idea to build a 72-clock stereo | |
recorder chip. It uses this nested chip as "tape": | |
Delay line made of 35 inverters in one chip | |
That chip uses 190 bytes The master chip uses 4 instances of it: | |
72-clock stereo recorder diagram | |
The total size is 852 bytes, so there's still room for some more | |
inverters in case a recording of more than 72 clocks is needed | |
(remember the maximum is 1024 bytes). A mono recorder of about 150 | |
clocks would also be possible. | |
When I was checking the design I noticed an anomaly which seems to be | |
a bug. I don't know if that bug was removed in v1.1. It's in the | |
input of one of the inverters in the nested chip: | |
Possible bug in RO | |
It would probably be possible to make a "quad recorder", though the | |
controlling logic would also take space. The idea is to have four | |
pins for output, a recording input, an erase input and two "tape | |
select" inputs that would make the recording and erasing pins act on | |
the desired tape. I estimate that it can be done using eight extra | |
ANDs and four inverters. | |
## Count to N chip | |
This is a TkGate diagram of the chip. It's somewhat complex. It has | |
five nested chips, three of one kind and two of another. Both nested | |
chip types are the same thing except for the pin layout, probably to | |
avoid too many crossings. I've titled them LNC (Left Nested Chip) and | |
RNC (Right Nested Chip). | |
Count-to-N chip diagram | |
The LNC: | |
Count-to-N chip diagram, LNC | |
The RNC: | |
Count-to-N chip diagram, RNC | |
This time I didn't take the effort to draw the junctions in RO-style. | |
I have placed buffers because TkGate doesn't allow me to interconnect | |
two module outputs. For the simulation I used the same flip-flop as | |
in the Wall Hugger. In order for the simulation to work properly, I | |
needed to adjust the inverter to a custom delay of 8 cycles. | |
Every nested chip is a bit in the chain. Let's examine just the LNC, | |
as the RNC is the same with some pins different. But first, note that | |
the inverter plus the AND gate make a raising edge detector that | |
throws a 1-clock pulse every time the count pin is active. | |
Pin 7 is obviously the reset pin. When it is activated, the flipflop | |
is reset. | |
Pin 6 is the Pulse input. | |
Pin 8 is the Previous Output input pin. When it is 1, it means that | |
the previous output is set, so we're next. When that happens, the AND | |
gate gives permission to the counting pulse to pass through and set | |
the flipflop. | |
When the flipflop is set, it must be reset at the next counting | |
pulse, so the output is fed back to the Reset input through an AND | |
gate with the counting pulse. | |
Pin 5 is the Next Output pin for chaining. Pin 2 is for connecting to | |
the main chip's pin. | |
Now for the main chip circuit. There are five chips to feed five | |
outputs, plus two extra flip flops. The lower one in the diagram is | |
initialized to 1 on reset, because it acts as the "previous output" | |
for the first nested chip, so that it knows it's its turn. It is | |
reset by the output of that first nested chip. | |
The upper flipflop is the last bit in the chain. That bit has a | |
special treatment because it must not be reset on the next pulse, | |
only on global reset. | |
From: https://web.archive.org/web/20180131084757/http://www.formauri.es/persona… | |
# 2014-01-24 - The Hardest Computer Game of All Time by David Auerbach | |
It was called Robot Odyssey, it took me 13 years to finish it, and it | |
sealed my fate as a programmer. | |
My first computer was an Apple IIe with 128KB of RAM, no hard drive, | |
and a 5-1/4" floppy drive. One of the top educational games back then | |
was Rocky's Boots, an inventive game that taught the basics of formal | |
logic to kids. I loved it when I was 6. Two years later, I got Robot | |
Odyssey, which promised to expand on Rocky's Boots by extending the | |
formal logic to actual programming. The game devastated me. My brain | |
could not comprehend how to solve its puzzles. I finally finished | |
it--13 years later, and not without some assistance. | |
Let me say: Any kid who completes this game while still a kid (I know | |
only one, who also is one of the smartest programmers I've ever met) | |
is guaranteed a career as a software engineer. Hell, any adult who | |
can complete this game should go into engineering. Robot Odyssey is | |
the hardest damn "educational" game ever made. It is also a stunning | |
technical achievement, and one of the most innovative games of the | |
Apple IIe era. | |
Visionary, absurdly difficult games such as this gain cult | |
followings. It is the game I remember most from my childhood. It is | |
the game I love (and despise) the most, because it was the hardest, | |
the most complex, the most challenging. The world it presented was | |
like being exposed to Plato's forms, a secret, nonphysical realm of | |
pure ideas and logic. The challenge of the game--and it was one | |
serious challenge--was to understand that other world. Programmer | |
Thomas Foote had just started college when he picked up the game: "I | |
swore to myself," he told me, "that as God is my witness, I would | |
finish this game before I finished college. I managed to do it, but | |
just barely." | |
Programming in your pajamas: the simulation by Gil Morales | |
In Robot Odyssey, you played a character who falls in a dream into | |
the mysterious city of Robotropolis. There were five ascending levels | |
to Robotropolis before you could return back home. Here's a rough | |
estimate of their difficulty: | |
Level Difficulty | |
------------------------- -------------- | |
The Sewer Moderate | |
The Subway Challenging | |
The Townj Very Difficult | |
The Master Control Center Impossible | |
The Skyways Impossible | |
Robotropolis as rendered by Gil Morales | |
By my teenage years I'd completed the first three levels, but my | |
siblings and I hit a brick wall with the fourth level, which is to | |
earlier levels like algebra is to arithmetic. (As Thomas Foote said, | |
"I was stuck on this level for most of my college years.") The fifth | |
level was nothing more than a fabled dream. The Internet didn't exist | |
in those days, and even finding someone else who had played the game | |
was difficult if you didn't live in Silicon Valley. | |
The game became my bĂȘte noire, a lingering reminder of my inadequacy. | |
To give you some idea, I couldn't get past the fourth level even | |
after I'd been programming in BASIC and Pascal for years. | |
The game had a profound effect on those who played it. My younger | |
brother, who suffered with my sister and me as we struggled through | |
the game, told me, "It's where I started on the road to becoming a | |
programmer." Even if players got stuck (and everyone got stuck), the | |
game offered ideas and concepts that no other game did. Game designer | |
and hardware hacker Quinn Dunki of One Girl, One Laptop wrote Gate, a | |
spiritual successor to Robot Odyssey that employed many of the same | |
concepts. The tech law professor James Grimmelmann told me it had | |
been his "game for a rainy decade," describing an immense sense of | |
accomplishment on finishing one of the nastier puzzles--"a big part | |
of why I loved programming." Programmer/musician/hacker Joan Touzet | |
used it to teach programming to middle schoolers--in 2004. Thomas | |
Foote was so taken with the game that he spent years re-implementing | |
the entire game in Java, with the support of a small but dedicated | |
fan community. (One of them remembers completing the game and getting | |
a certificate from the Learning Company declaring him the 34th person | |
to finish.) Foote called his version DroidQuest, and it is the | |
easiest way to play Robot Odyssey today. | |
Gate by Quinn Dunki | |
It's an accomplishment. | |
Software engineer Micah Elizabeth Scott, who ported the game to the | |
Nintendo DS, told me that Robot Odyssey "played a large role in | |
shaping who I'd later become," and emphasized just how personal and | |
distinctive a creation it was: "You see the style of an individual or | |
a very small team, uncluttered by corporate structure or modern | |
abstractions." | |
It's a testament to the sheer free-spiritedness of the early days of | |
consumer software that such a game could even get made. The Learning | |
Company, who also made classics like Rocky's Boots, Reader Rabbit, | |
and Gertrude's Puzzles, was a small company founded in 1980 on an NSF | |
grant by three educators who had taken an interest in software: | |
Leslie Grimm, Ann McCormick, and Teri Perl, as well as Warren | |
Robinett (who had created the world's first Easter egg when he hid | |
his name in a secret room in Atari's Adventure).* The company was | |
atypical both in focusing on educational software and in being led by | |
women. Grimm and Robinett designed 1982's Rocky's Boots, which taught | |
Boolean logic gates to kids, and which had captivated my 6-year-old | |
self. Grimm also co-authored Robot Odyssey, which began as the | |
brainchild of Michael Wallace, a 22-year-old Stanford undergrad at | |
the time. | |
The game taunts you | |
Wallace told me that writing the game was one of the best times of | |
his life. Originally a customer service rep at the Learning Company, | |
Wallace taught himself to code in Apple 6502 assembly by looking at | |
Robinett's code for Rocky's Boots. After Robinett left the company, | |
Wallace expanded Robinett's code to architect the underlying | |
technology for Robot Odyssey, including the dazzling ability to embed | |
circuits within circuits. Doing this was no easy task; Wallace called | |
it "an art form" and recounted working 100 hours a week. When Teri | |
Perl described the project to legendary computer scientist Alan Kay, | |
he said, "You're wasting your time. It can't be done." That is, the | |
basic idea was simply too complex to run on an Apple home computer. | |
When Robot Odyssey shipped, the company gave Wallace a plaque that | |
said, "It can't be done. --Alan Kay." | |
After getting her Ph.D. in biology from Stanford, Leslie Grimm became | |
fascinated by computers and their educational potential while | |
volunteering in her daughter's school. In addition to directing the | |
entire project, Grimm was in charge of the game portion of Robot | |
Odyssey: the five levels of Robotropolis and three tutorials | |
(expanded to five tutorials in Version 1.1, in the hopes of making | |
the game a bit more tractable to players). Each of the five game | |
levels was the personal creation of a single person. I'd like to | |
single out Shaun Gordon, the 16-year-old high school whiz who | |
designed the diabolical fourth level, the Master Control Center, | |
which was the Waterloo for many a player (including myself). | |
Wallace was kept so busy with the plumbing of the game that he | |
himself never played it through to completion. I asked him if he | |
might try someday, and he said, "It might take a year of my life." He | |
wasn't sure that anyone at the Learning Company had solved the entire | |
game singlehandedly! | |
To solve the puzzles, you are given three (eventually four) robot | |
pals to wire and program. From left to right, they are Sparky, | |
Scanner, and Checkers. They can move, detect walls, pick up and drop | |
things, and communicate to one another. | |
Sparky, Scanner, and Checkers: they are yours to command... | |
When I say program, I mean something a bit more primitive than | |
computer code, even the low-level assembly that processing chips | |
natively run. I mean the actual logic gates (AND, OR, NOT) that make | |
up the innards of chips. So Robot Odyssey was programming, but it was | |
also electrical engineering. Your tools for implementing "programs" | |
were the most primitive available. You had "electricity" going | |
through wires into gates. The gates implemented the primitive | |
operations of formal Boolean logic. | |
Diagram | |
Boolean logic is fairly simple. It deals in two opposing values, | |
often called TRUE and FALSE (if logic is being applied to | |
assertions), but since we're talking about electricity here, they're | |
better called ON and OFF. The robots in the game have thrusters that | |
make them move. For example, if you feed electricity into a robot's | |
thruster through a wire that is ON, the thruster turns ON and the | |
robot moves. [1] In addition, there are assorted logic gates that | |
change the nature of the electricity. A NOT gate had one wire going | |
in and one wire coming out, and inverted the input wire. If the | |
incoming wire was ON and had electricity going through it, the gate | |
would not output electricity. If the incoming wire was OFF, the gate | |
would output electricity. [2] | |
A "wall hugger" robot. The actual logic is [in] the blue "2" chip. | |
Using these gates and a few others, you had to wire up robots to | |
perform tasks--reasonably simple ones at first, [3] but which became | |
increasingly complicated as the game progressed. | |
Eric Welsh's circuit that "plays" a 100110 pattern on the antenna. | |
When the task is to get one robot to communicate orders to move to | |
another robot through an antenna that can only be ON or OFF, those | |
logic gates start to seem awfully limited in their capabilities. The | |
trick is, they aren't limited--in sufficient combination, those | |
little logic gates can do anything. But it takes some real thought. | |
Getting these simple gates to execute complex programs melted my | |
brain. My child's mind was literally incapable of making the jump | |
from those simple gates to the complex control structures required to | |
solve the game's puzzles. The game offered you the ability to "burn" | |
circuits into chips in order to abstract control structures. Here's a | |
chip that uses a lot of OR gates in order to... well, I won't get | |
into it... | |
Inside a chip: Fun for the whole family! | |
The point being that those simple logic gates could, in sufficient | |
combination and organization, do tremendously complicated things. | |
That, after all, is the very stuff of computer programming, using | |
primitive operations in immensely complex architectures. For Foote, | |
the fundamental appeal of the game is much the same as the | |
fundamental appeal of mathematics and computer science: "The world is | |
logical, and operates under simple rules. From such simplicity can | |
come great complexity." | |
Though a planned sequel (the original box billed the game as Robot | |
Odyssey I) never materialized, the game won awards and a write-up in | |
Scientific American. The game got Wallace an audience with the top | |
brass at Apple and a presentation at Xerox PARC, and he went on to | |
design electronic toys including the Nintendo Power Glove and now has | |
his own company, Pure Imagination. Grimm stayed with the Learning | |
Company and authored many more games, including the successful Reader | |
Rabbit franchise, and more recently developed educational software | |
for deaf children. | |
The sheer complexity of Robot Odyssey made it the spiritual forebear | |
to today's sandbox games like Minecraft. It probably turned hundreds | |
of people into computer programmers, and in the hopes of making a few | |
more, I issue the Bitwise Robot Odyssey Challenge: The first reader | |
to complete Robot Odyssey--send a save game file to me as proof-- | |
gets a replica of the Robot Odyssey completion certificate from the | |
Learning Company. Only first-time players allowed--and no cheating by | |
looking up the solutions! | |
Notes: | |
[1] | |
If you stop the electricity flowing through the wire, the thruster | |
turns OFF and the robot stops moving. | |
[2] | |
An AND gate takes two inputs and outputs electricity if its two | |
inputs are both on. An OR gate outputs electricity if either or both | |
of its two inputs are on. An XOR gate (for exclusive-or) outputs | |
electricity if either of its two inputs are on, but not both. | |
[3] | |
Here's a simple example. Let's say you want a robot to move up when | |
its antenna is receiving a signal (when the antenna is ON), and move | |
down when the antenna is not receiving a signal (when the antenna is | |
OFF). You wire up the antenna output to the UP thruster so that when | |
the antenna is ON, the UP thruster turns on, and vice versa. You also | |
wire up the antenna output to the DOWN thruster, but put it through a | |
NOT gate first, which reverses the antenna output. So when the | |
antenna is ON, the DOWN thruster is OFF, and vice versa. | |
From: https://web.archive.org/web/20190414172920/https://slate.com/technology/2… | |
tags: retrocomputing | |
# Tags | |
retrocomputing |