The 1977 Trinity: How Three PCs Launched the Personal Computer Revolution

Introduction

In 1977, a quiet revolution sparked. Three machines—the Apple II, the Commodore PET 2001, and the Tandy Radio Shack TRS-80—arrived almost simultaneously, bringing computers out of hobbyist basements and into homes, schools, and small businesses. Before 1977, computers were either massive mainframes or do-it-yourself kits. These three were the first mass-produced, ready-to-use personal computers. This post explores their impact, hardware, and why they still matter today.

The State of Computing Before 1977

In the early 1970s, computers were room-sized behemoths owned by governments and large corporations. The microprocessor (e.g., Intel 4004, 1971) changed everything, but early hobbyist machines like the Altair 8800 (1975) required soldering and front-panel toggle switches. Only enthusiasts dared. Software was nonexistent; you had to write your own in machine code.

The 1977 Trinity

Three companies saw the potential: Apple, Commodore, and Tandy. Each released a complete system—keyboard, monitor, CPU, storage—marketed to non-technical users. Let's break them down.

Apple II (June 1977)

The Apple II was the star. Designed by Steve Wozniak and Steve Jobs, it featured:

• CPU: MOS Technology 6502 at 1 MHz
• RAM: 4 KB (expandable to 48 KB)
• Storage: Cassette tape (later floppy disk)
• Display: Color graphics and text via TV
• Price: $1,298 (about $6,500 today)

Its killer feature? Color and expandability. The Apple II had eight internal expansion slots, allowing users to add everything from floppy drives (the Disk II, 1978) to printers and modems. This made it a platform for innovation, including the first spreadsheet—VisiCalc (1979)—which turned the Apple II into a business essential.

Commodore PET 2001 (October 1977)

Commodore, led by Jack Tramiel, aimed for the education and home market. The PET featured:

• CPU: MOS 6502 at 1 MHz
• RAM: 4 KB (expandable to 32 KB)
• Storage: Built-in cassette deck
• Display: Monochrome 9-inch monitor, 40×25 text
• Price: $795 (about $4,000 today)

The PET was an all-in-one: keyboard, monitor, and storage in a single unit. Its BASIC in ROM meant instant programming. Schools loved it for computer literacy. Though less expandable than the Apple II, its solid construction and affordability made it a hit.

Tandy Radio Shack TRS-80 (August 1977)

Radio Shack, with thousands of retail stores, sold the TRS-80 Model I. Specs:

• CPU: Zilog Z80 at 1.77 MHz
• RAM: 4 KB (expandable to 48 KB)
• Storage: Cassette tape
• Display: Monochrome, 64×16 text
• Price: $599 (about $3,000 today)

Sold through its massive retail chain, the TRS-80 was the first PC for many households. Its Z80 CPU distinguished it from the 6502 machines. The TRS-80 had a robust library of software, including the first word processor, Electric Pencil, and business tools.

Code Example: Programming the 1977 PCs

To understand these machines, nothing beats writing a simple program. All three shipped with BASIC. Here's a classic "Hello, World" on the Apple II:

10 PRINT "HELLO, WORLD!"
20 END

For the TRS-80, BASIC was nearly identical:

10 PRINT "HELLO, WORLD!"
20 END

But PET BASIC had a quirk: string variables required DIM:

10 DIM A$
20 A$ = "HELLO, WORLD!"
30 PRINT A$
40 END

Impact on Software Development

The 1977 trinity created the home computer software market. Here are key milestones:

• 1979: VisiCalc for Apple II—the first spreadsheet.
• 1981: IBM PC launched, but 1977 machines had already defined the market.
• 1984: Macintosh, inspired by Apple II's user-friendliness.

Modern Derivations

Today's programming owes much to those early days. For example, writing a simple BASIC interpreter is a classic exercise. Here's a skeleton in Python:

def execute_basic(code):
    for line in code.split('\n'):
        if line.startswith('PRINT'):
            print(line.replace('PRINT', '').strip())

# Example usage:
execute_basic('PRINT "HELLO, WORLD!"')

(Note: Real interpreters are complex, but this illustrates the principle.)

Why 1977 Matters Today

These three machines established:

1. Open architecture (Apple II slots)
2. Integrated all-in-one design (PET)
3. Retail distribution (TRS-80 at Radio Shack)

They democratized computing, enabling a generation of programmers, entrepreneurs, and hobbyists. The legacy is visible in every modern PC, laptop, and smartphone.

Conclusion

In 1977, the personal computer was born. The Apple II, Commodore PET, and Tandy TRS-80 each took a different path—but together they proved that computers could be for everyone. Next time you reach for a smartphone, remember its ancestors: beige boxes with cassette drives and 4 KB of RAM.

Further Reading

• Apple II History — comprehensive resource.
• Commodore PET — specifications and preservation.
• TRS-80 Model I — technical details and software.

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This post is part of Tanok Tech's retro computing series. We build modern software but respect the pioneers who made it possible.