Gameplay

Platform: Commodore PET

Commodore PET: the all‑in‑one micro that taught a generation to play and program

When people talk about early video game platforms, they often jump straight to home consoles or to home computers that had joysticks and color sprites. The Commodore PET remains a quieter legend. It arrived in 1977 as an all‑in‑one personal computer with a built‑in screen and cassette deck, sold into schools and offices, and yet it still fostered a distinct game culture. Students sneaked in rounds of ASCII Star Trek between math exercises, teachers typed in BASIC listings from magazines, and hobbyists learned 6502 assembly by squeezing responsive arcade clones into a character grid. It was practical, it was sturdy, and it made room for play.

If you’ve never met one in person, imagine a compact, wedge‑shaped machine with a crisp green monochrome display and a keyboard that looks like it came from a serious calculator. It is not sleek by modern standards, but it radiates purpose. And it is more influential than its square edges suggest. The PET formed one point of 1977’s famous microcomputer "trinity" along with the Apple II and the TRS‑80. As a platform, it bridged business and education with a surprising side career in games.

This article explores how the PET came to be, what made it different, how people actually played games on it, and why it still matters if you love video game history. I will mix practical details with a few anecdotes, because the PET invites that kind of storytelling.

Context and launch

The PET appeared at the right moment. In early 1977, Commodore was uniquely positioned to build a complete microcomputer. It had acquired MOS Technology, maker of the 6502 CPU, and it owned calculator factories, case design, and distribution. Commodore could build most parts itself and ship at aggressive prices.

The name stood for "Personal Electronic Transactor", a bit of business‑speak that hinted at its initial market. The first PETs were demonstrated at the Winter CES in January 1977, and shipments began later that year. They were designed by a small team led by Chuck Peddle, the same engineer who championed the 6502. The original model, the PET 2001, had a 9‑inch monitor, an integrated cassette recorder, and a distinctive "chiclet" keyboard that looked cute until you tried to write a term paper on it.

Commodore kept refining the line. The 2001’s keyboard was quickly replaced by a full‑travel version, the built‑in cassette moved out to become an external unit called the datasette, and the family branched into the 3000, 4000, and then 8000 series with larger screens and more RAM. In North America the machines were marketed as PETs, while in parts of Europe the same hardware often carried the CBM brand to emphasize business use.

Even though the PET was marketed as a general‑purpose computer, it earned an early reputation as a great school machine. It was robust, had a built‑in display, and booted straight to Commodore BASIC, which meant you could type a program immediately. That combination made it a natural platform for both educational software and for the kind of informal gaming that thrives in classrooms.

For a factual overview of models and history, the Wikipedia page on the Commodore PET is a solid reference.

Hardware overview

From the outside, a PET looks like a single appliance. On the inside, it is a tidy 1970s microcomputer with a CPU, RAM, ROM, a character display, and a few versatile I/O chips.

  • CPU: MOS Technology 6502 at roughly 1 MHz. The same family of processor later powered the VIC‑20, Commodore 64, Apple II, and NES.
  • RAM: early 2001 units shipped with 4 KB or 8 KB, expandable; later PETs commonly offered 16 KB or 32 KB standard, and some 8000‑series machines like the 8096 provided 96 KB through banked memory.
  • ROM and OS: Commodore BASIC (derived from Microsoft’s 6502 BASIC) lived in ROM alongside the screen editor and the KERNAL system routines. BASIC revisions progressed from 1.0 to 2.0 to 4.0, with 4.0 adding more disk and I/O features.
  • Display: built‑in monochrome CRT, 40 columns by 25 rows on the 2001/3000/4000 series and 80 columns by 25 rows on many 8000‑series machines. Later 80‑column PETs used a CRTC controller compatible with the Motorola 6845 family.
  • Character set: the distinctive PETSCII character set, which added line‑drawing, block, and card symbols to uppercase letters. It is simultaneously limiting and delightfully expressive. If you want a deeper dive into the art and hacks that grew around it, see PETSCII on Wikipedia.
  • Storage: cassette tape via the datasette as standard, with optional IEEE‑488 floppy drives.
  • Ports: IEEE‑488 (also known as GPIB) for printers and disk drives, one or more cassette connectors, and internal headers that third parties used for expansion.

On paper, none of that screams "game machine". No hardware sprites, no sound chip, and never any color. Yet the PET’s constraints pushed creativity in a way that defined its game library.

Display, graphics, and text

The PET’s display is character based. Each position on screen holds one character from the PETSCII set. There is no pixel addressability in the way later home computers offered, so most graphics are composed from characters, reverse video, and block elements. Programmers leaned hard on this. If you have never seen a space invader built from PETSCII blocks and brackets, you are missing an aesthetic experience.

Screen updates happen by writing to screen memory, which the BASIC interpreter exposes through PRINT and the ability to embed control codes. In assembly language, you can move bytes directly for faster action. The 40‑column PETs update more quickly than 80‑column units, which makes some games feel snappier on earlier models. Developers learned to avoid redrawing the entire screen and instead poked just the characters that changed, which gives PET games their flicker‑free minimalism.

There is also a font trick that veterans remember fondly: switching between uppercase graphics and uppercase‑lowercase modes changes the character shapes, which can subtly transform the look of a game. Many titles shipped with instructions like "press SHIFT+RUN/STOP, then type POKE 59468,14" to set up the right mode. The ritual was half the fun.

Sound, or how to play in silence

The PET shipped without dedicated sound hardware, and the early models did not include a speaker. Some later variants offered a simple click, but for the most part you played in silence. Resourceful programmers turned silence into a feature. They used visual effects for feedback, timed delays to create rhythm, and in certain cases toggled I/O lines to make a relay click. If you were sitting close to the machine and the room was quiet, a game could be punctuated by the faint chatter of hardware doing its best impression of percussion.

The absence of sound also made the PET very classroom friendly. You could get away with a quick game as long as you looked serious and typed occasionally.

Storage and peripherals

The tape drive, known as the datasette, defined daily life with a PET. You learned to keep backups and to name files carefully, and you learned patience. Loading from cassette was dependable with practice but never fast. The PET’s BASIC offered straightforward commands like LOAD and SAVE. The integrated cassette deck on the original 2001 made it feel like a self‑contained workstation, while later models used external cassette units connected by a dedicated port.

For serious work and for larger games, Commodore offered floppy drives that connected over the IEEE‑488 bus. This standard, also called GPIB, came from lab equipment and allowed daisy chaining multiple devices in a stable, protocol‑based way that was ahead of most consumer machines of the time. If this kind of historical interface tickles your curiosity, there is a concise overview on Wikipedia about IEEE‑488.

Printers and plotters were common in schools and offices, and students often discovered that a plotted maze or line drawing felt like a kind of game output. The PET also supported dual cassette drives on some models, which helped with copying and with classroom setups where the teacher distributed programs on tape.

Programming environment

The PET booted straight into Commodore BASIC, which made it an approachable machine for beginners. You could type 10 PRINT "HELLO", hit Return, and see it run. Games written in BASIC were a natural first step. Magazines printed listings, books taught structured programming through text adventures and numeric puzzles, and students modded games by changing variables and strings. The PET’s BASIC was efficient and well documented, and it included PEEK and POKE to reach into memory‑mapped I/O, which let simple BASIC programs do dramatic things.

Assembly language took PET games further. Because the PET used the 6502, there was excellent documentation and a community of enthusiasts writing routines for fast character movement, keyboard reading, and cassette I/O. Commodore and third‑party vendors offered machine language monitors and assemblers. Later on, the SuperPET variant included additional languages like Pascal, APL, and FORTRAN courtesy of a second processor and custom ROMs developed with the University of Waterloo. That machine is a fascinating fork in the PET family tree, and its story is covered in the SuperPET article on Wikipedia.

For game developers, this environment shaped the culture: start in BASIC, then optimize hot loops in assembly, and sprinkle in clever PETSCII art. It is not hard to see the line from that experience straight to the demo scenes that blossomed on later Commodore machines.

Notable models and their gaming flavor

There were several iterations of the PET, and while they share a lineage, they feel different in practice. The early PET 2001 with the chiclet keyboard and built‑in cassette is charming and inconvenient for long play sessions. The later 4000 series with a full keyboard and 40 columns strikes a sweet spot for fast character animation. The 8000 series with 80 columns is brilliant for productivity and for text adventures, since it can display more information at once, but it can be slower for arcade‑style games if the code touches many characters per frame.

The SuperPET is an outlier for games in the arcade sense, but it is a powerhouse for interactive fiction and educational software. Its 80‑column screen and bundled languages made it a favorite in universities. You will see it in photos of computer labs from the early 1980s.

Game library and standout titles

On the PET, "iconic" does not always mean "commercial blockbuster". The platform’s most beloved games often came from magazine listings, school collections, and small publishers that embraced the PET’s strengths. A few categories stand out.

Text adventures flourished. The PET’s clear text display and keyboard made it a natural home for early interactive fiction. Many players first encountered the genre through Adventure International titles by Scott Adams. The original 1978 hit Adventureland made its way onto the PET and taught a generation the rhythm of "GET LAMP" and "NORTH". If you are curious about that pioneering title, the Adventureland page on Wikipedia is a good snapshot.

Strategy and simulation games were also at home on the PET. Star Trek variations, derived from the mainframe classic, were immensely popular. You plotted photon torpedoes, watched your energy reserves, and played long sessions that felt almost meditative on the green screen. Businesslike titles like "Lemonade" and "Hamurabi", descendants of classic BASIC exercises, were common in classrooms and left a strong memory partly because teachers could justify them as learning tools.

Arcade clones existed in abundance, even if the machine was not built for sprite flinging. Developers created compelling variations on Space Invaders, Breakout, and Asteroids using PETSCII shapes and tightly written loops. The best of these games feel crisp despite the lack of graphics hardware, and in some ways they age elegantly because they do not try to fake what the PET cannot do.

Puzzle and board games rounded out the catalog. Reversi, Othello, Mastermind, and Gomoku variants were ubiquitous, and many were surprisingly strong opponents. I remember being thrashed by a PET Othello program that explained its moves with little text hints. It was a formative lesson in accepting defeat graciously when your opponent runs on a 1 MHz CPU.

Later, the PET homebrew scene embraced the machine’s identity with projects that leaned into PETSCII art in sophisticated ways. If you explore modern retro communities, you will find contemporary releases that run on real PET hardware and on emulators, sometimes shared as type‑in listings just for fun.

How games played on the PET

Because the PET’s hardware is character based, developers thought differently about animation and responsiveness. Game loops typically updated only the specific characters that needed to move. That meant a snake game moved a head and a tail without reprinting the whole screen. Collision detection often checked the character value in the target cell. Scrolling was usually simulated by shifting blocks rather than moving a viewport, which gives PET action games their distinctive staccato style.

Input was read from the keyboard matrix, so many arcade‑style games used WASD or IJKL long before that became meme‑worthy. There was no standardized joystick on early PETs, though third‑party adapters and hacks existed. The lack of a joystick arguably made players more comfortable with text adventures and strategy titles, which reinforced the platform’s identity.

Cassette storage influenced design as well. Games had to load cleanly and quickly, and many were partitioned into modules. A text adventure might load a small kernel and then fetch different rooms from tape or disk as needed, with a tasteful pause and a prompt reminding you to press Play on tape. Those pauses became part of the experience.

Community, distribution, and magazines

The PET’s game culture did not revolve around a single blockbuster publisher. It grew through community. Teachers and students traded cassettes at club meetings, typed in listings from books, and learned from each other. Commodore itself fostered this with curated tape magazines and with documentation that encouraged experimentation.

One influential technical publication, The Transactor, covered Commodore computers in depth and frequently shared code and techniques that fed into better games and utilities. It was the kind of magazine you kept next to the machine with the spine creased at the PEEK/POKE tables. Its role as a nexus for Commodore developers is acknowledged in many retrospectives and its own Wikipedia entry captures that spirit.

This environment shaped the PET’s distribution of software. Lots of public domain and shareware titles circulated, and small publishers sold catalog tapes of games and educational programs. For people who grew up with these machines, the PET’s game library feels more like a living archive than a retail shelf.

Impact on the industry and legacy

Measured strictly as a game platform, the PET seems modest next to later Commodore hits like the VIC‑20 and Commodore 64. Yet its influence on video games is significant in at least three ways.

First, it seeded a generation of programmers. Many of the developers who created commercial games in the early 1980s learned to code on a PET. They absorbed lessons about tight loops, input handling, and player feedback that carried forward, even when later machines added color and sound. A 1 MHz CPU and a character map make you respect every cycle.

Second, it helped normalize the idea that a personal computer could be both serious and playful. That duality informed how parents and schools justified buying computers, and it shaped how companies marketed later models. The PET made it socially acceptable for a classroom to host a game, provided it wore a math hat.

Third, it established Commodore’s ecosystem and vertical integration. By mastering the 6502 supply chain and by building peripherals like the datasette and IEEE‑488 drives, Commodore created a platform story that set up the affordable VIC‑20 and then the culture‑defining C64. Much of the C64’s game development scene, including its demo community, traces social and technical lineage to PET owners and clubs.

PET in education and business

Beyond hobbyists, the PET had heavy uptake in schools and small businesses. In the UK and parts of Europe, many classrooms received PETs because they were durable and all‑in‑one. Students learned BASIC on green screens, typed reports, and played carefully selected games. Some of those games were deliberately educational, drilled times tables, or taught logic through puzzles. Others were stealth learning: Star Trek made you think about resource management; "Hammurabi" taught scarcity and tradeoffs.

In business settings, PETs ran inventory systems, word processors, and simple databases. That seriousness rubbed off on the game culture. Games on the PET often looked like tools and ran in windows of spare time. You were never more than a keystroke away from a spreadsheet or a word processor, at least in theory.

Modern emulation and preservation

You can experience PET games today without hunting for vintage hardware. The long‑standing VICE emulator supports the PET family along with other Commodore machines. It is actively maintained and runs on modern operating systems, and it does a remarkably good job with timing and display quirks. If you want to try PET software quickly, VICE is the place to start. The project’s homepage is here: VICE, the Versatile Commodore Emulator.

There are also curated archives of PET software, including text adventures and educational titles. Many of these come with documentation and cover art that give you a sense of their original context. If you do have real hardware, modern projects offer SD‑card storage solutions that emulate IEEE‑488 devices or datasette behavior, which makes living with a PET easier in the twenty‑first century.

One small tip if you jump into emulation: start with a 40‑column PET for arcade‑style games, then switch to an 80‑column SuperPET configuration for text adventures and development languages. That combination gives you a balanced sense of the platform’s range.

Curiosities and anecdotes

The PET accumulated a healthy catalog of lore over the decades. A few bits stand out for game fans.

  • "Killer poke": early PET models lacked a CRTC and were sensitive to certain POKE sequences that could push the display hardware beyond design limits. Enthusiasts discovered a memory poke that made screen editing faster on some machines, which in later CRT‑based models could damage the monitor. The phrase "killer poke" stuck. It is a reminder that on these early computers, you really could reach out and touch the hardware from BASIC.

  • On‑screen charisma: the PET’s green phosphor display is not just colorless, it has a specific glow and persistence that makes PETSCII art look pleasing in a way that emulation only approximates. A simple maze or a starfield suddenly looks cinematic on the real hardware.

  • In the movies: sharp‑eyed viewers have spotted PETs in late 1970s and early 1980s films. The machine’s distinctive profile made it a favorite prop when directors wanted something that said "futuristic computer" with no explanation required. Lists of on‑screen appearances circulate among fans, and once you notice the PET in a scene, it is hard to unsee it.

  • Canadian connection: the University of Waterloo partnership that yielded the SuperPET reflected a broader pattern of PET use in Canadian education and research. That collaboration gave the PET a second identity as a platform for language development and compiler courses.

  • Keyboard stories: if you learned to type on a PET, you probably still press Return with authority. The full‑travel keyboards on later models were satisfyingly clicky, and even the maligned chiclet keys on the original left a sensory memory. In many classrooms, the sound of a dozen PET keyboards is the sound of the early micro era.

As for personal memories, discovering that a relay click could pass as a "laser" in a space game felt like a magic trick. It is the kind of hack that makes you love a machine.

Constraints that shaped design

The PET’s limits were creative catalysts. Because the PET had no pixel graphics, artists learned PETSCII composition. Because it had no sound chip, designers focused on timing and pacing, which often produced surprisingly readable games. Because storage was slow, developers built small, modular programs that loaded quickly and resumed gracefully after errors.

Even the keyboard influenced design. Without a joystick standard, control schemes settled around keys you could find by touch. That made games like action mazes feel almost like rhythm exercises, where you learned to tap out patterns.

And because BASIC was the default, a large fraction of games were readable, moddable, and teachable. Players became co‑authors, which fostered a culture of sharing and improvement. It is hard to overstate how different that feels compared to sealed consoles of the same era.

Why it still matters to game history

If you work in games or care about their craft, the PET is a master class in doing more with less. It is a laboratory where you can see how gameplay survives without fancy assets. It reminds you that a tight control loop, clear feedback, and a good idea trump raw horsepower.

The PET also anchors an important chapter in the story of accessibility. Affordable, approachable, and ubiquitous in some school systems, it let many kids try real programming. A nontrivial number of those kids eventually wrote commercial games. Some wrote tools that others used to write games. The ripple effect is everywhere.

Finally, the PET’s aesthetic left fingerprints on retro culture. PETSCII art is a living tradition, vibrant in online communities. Character‑grid games are still a niche in jam scenes. And the attitude that says "I can build this myself" has not gone out of style. If anything, it is the engine of today’s indie scene.

Tips for exploring PET games today

If you want to sample the PET library with an eye to its strongest suits, think in arcs rather than titles. Start with a text adventure such as Adventure International’s "Adventureland" to feel how the 80‑column display elevates narrative. Then try a simple arcade clone in 40 columns to appreciate crisp PETSCII animation. Follow that with a strategy classic like Star Trek to enjoy slow‑burn tension without graphics, and finish with a puzzle or board game to admire bite‑sized AI written in a few kilobytes.

Treat type‑in listings as playable artifacts. Reading the code is part of the experience. Modify a constant and see what breaks. If you are using VICE, map a few keyboard shortcuts so you can reset quickly, and keep a notepad handy for PEEK/POKE experiments.

Final thoughts

The Commodore PET was never a dedicated video game machine, yet it was a genuine game platform. It invited people to create, to share, and to play within clear limits. It helped seed the culture and the skills that produced some of the most beloved microcomputer games of the 1980s. It remains a rewarding platform to explore precisely because of its constraints. If you like learning from the past, a few hours with a PET emulator and a handful of classic programs will make you smile and probably teach you something useful about making games today.

Further reading and tools worth bookmarking:

If you came to the PET through nostalgia, welcome back. If you are discovering it for the first time, enjoy the rabbit hole. It is greener and more charming than you might expect.

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