Apple I
 | |
| Original Apple I "NTI" motherboard (1976) | |
| Specifications | |
|---|---|
| Developer | Apple Computer Company (Steve Wozniak) |
| Manufacturer | Apple Computer Company |
| Type | Single‑board personal computer |
| Released | April 11, 1976 |
| Discontinued | September 30, 1977 |
| Intro price | US$666.66 (board only) |
| Units sold | ~200 |
| CPU | MOS 6502 @ 1 MHz |
| Memory | 4 KB RAM (standard) Expandable to 48 KB |
| Storage | 1200‑baud cassette interface (optional) |
| Display | Composite video – 40 × 24 uppercase text |
| Sound | — |
| Dimensions | 15 in × 9 in bare PCB |
| Weight | ≈ 1.6 lb (board) |
| OS / Firmware | 256‑byte WOZ Monitor ROM • Integer BASIC on cassette |
| Successor | Apple II |
| Model no. | "Byte Shop" & "NTI" revisions |
The Apple I (also styled Apple‑1) was Apple Computer Company's first commercial product and the machine that launched the personal computer revolution.[1][2] Hand‑built by Steve Wozniak and marketed by Steve Jobs from a Los Altos garage, it proved there was demand for pre‑assembled microcomputers and financed development of the groundbreaking Apple II.[3]
Historical Context
[edit | edit source]By March 1, 1976, Wozniak completed the basic design of his computer after being inspired by demonstrations at the Homebrew Computer Club and his desire to make affordable computing accessible to hobbyists.[4] The development was directly enabled by the revolutionary MOS 6502 processor, which debuted in 1975 at just $25—compared to $175 for competing Intel 8080 and Motorola 6800 processors.[5]
Key Historical Milestones
[edit | edit source]- Homebrew origins: Designed for the Homebrew Computer Club; early prototypes were wire‑wrapped before the green fiberglass production board
- Byte Shop breakthrough: Paul Terrell ordered 50 fully assembled boards at US$500 each, forcing Apple to move from kits to finished hardware[6]
- Seed capital: Wozniak sold his HP‑65 calculator for $500 and Jobs sold his VW Microbus for $1,500 to fund the first batch of parts, raising $1,300 total[7]
- Pricing quirk: The retail price of US$666.66 reflected Wozniak's fondness for repeating digits and delivered a one‑third markup on the $500 wholesale cost[8]
Technical Architecture
[edit | edit source]| Component | Specification | Details |
|---|---|---|
| CPU | MOS 6502 @ 1.023 MHz | 2/7 × NTSC color subcarrier (14.31818 MHz ÷ 14) |
| Memory Architecture | 4 KB standard, 48 KB maximum | 8 KB, 12 KB, 16 KB, 20 KB, 24 KB, 32 KB, 48 KB configurations |
| ROM | 256 bytes | WOZ Monitor at $FF00–$FFFF |
| Video System | 40 × 24 character display | 7-bit ASCII, uppercase only, 60 Hz refresh |
| I/O Interfaces | Composite video, ASCII keyboard | TTL-compatible, positive video logic |
| Expansion | Edge connectors | 44-pin bus, cassette interface optional |
| Power Requirements | +5V @ 3A, +12V @ 0.5A, -5V @ 0.2A | Unregulated supply, on-board regulation |
Processor Details
[edit | edit source]The Apple I was among the first computers to use the revolutionary MOS Technology 6502 processor.[9] Key specifications:
- 8-bit microprocessor with 16-bit address bus (64 KB address space)
- 56 instructions (early Apple I units had 55 instructions, missing ROR)
- $25 retail price in 1975 (equivalent to ~$140 in 2025)
- 1 MHz maximum speed (Apple I ran at 1.023 MHz for NTSC video timing)
- Registers: 8-bit Accumulator, X/Y Index registers, Stack Pointer, Program Counter, Status register
Memory Configuration
[edit | edit source]| Address Range | Size | Function |
|---|---|---|
| $0000–$0FFF | 4 KB | RAM (standard configuration) |
| $1000–$BFFF | 44 KB | Additional RAM (optional expansion) |
| $C000–$CFFF | 4 KB | Peripheral interface area |
| $D000–$DFFF | 4 KB | ROM expansion area (unused) |
| $E000–$EFFF | 4 KB | Integer BASIC ROM area (when loaded) |
| $F000–$FEFF | 3.75 KB | Monitor ROM area (unused) |
| $FF00–$FFFF | 256 bytes | WOZ Monitor ROM |
Video Display System
[edit | edit source]The Apple I's video system was revolutionary for its time, providing a complete TV-compatible display:[10]
- Character matrix: 40 columns × 24 rows (960 characters total)
- Character set: 7-bit ASCII, uppercase letters and symbols only
- Display timing: 60 Hz vertical, 15.75 kHz horizontal (NTSC compatible)
- Video output: 1V p-p composite video, positive sync
- Character generator: 5×7 dot matrix in 7×8 character cell
- Memory usage: 960 bytes for screen buffer ($D000–$D3BF)
Production Variants
[edit | edit source]The Apple I was manufactured in two distinct production runs with notable differences:[11][12]
| Variant | Production Period | Quantity | Distinguishing Features |
|---|---|---|---|
| Byte Shop Boards | April 1976 | ~50-75 units | • Hand-soldered components • No silkscreen legend • Round ceramic decoupling capacitors • Hand-written serial numbers (01-00##) • Some ceramic CPU/PIA chips |
| NTI Boards | Late 1976 | ~125-150 units | • PCB manufactured by North Star Technical (NTI) • White silkscreen legend with "NTI" marking • Square multilayer capacitors (usually green) • Improved component layout • Quality control stickers/stamps |
Component Analysis
[edit | edit source]Early Apple I boards show fascinating variations reflecting the transition from hobbyist to commercial production:
- Capacitors: Byte Shop boards used brown/blue disc ceramics; NTI boards featured green multilayer types
- Trimmer resistors: First batch used Spectrol potentiometers; second batch used Bourns metal film trimmers
- IC packages: Mix of ceramic (premium) and plastic (cost-reduced) packages
- Assembly quality: Hand-soldered first batch vs. wave-soldered production boards
Software & Operation
[edit | edit source]Upon power-up, the Apple I drops into the WOZ Monitor at the backslash prompt. The 256-byte monitor ROM provided essential system functions:[13]
| Command | Function | Example |
|---|---|---|
| R | Run program from address | E000R (start BASIC) |
| address: | Examine/modify memory | 300: A9 00 (store $A9 $00) |
| . | Print register contents | Shows A, X, Y, P, S registers |
| G | Go (continue execution) | Resume after breakpoint |
| Ctrl+C | Return to monitor | Break out of running program |
Software Ecosystem
[edit | edit source]Apple provided several software offerings on cassette tape:
- Integer BASIC – 4K BASIC interpreter by Steve Wozniak
- Blackjack – Card game demonstration
- Star Trek – Text-based space exploration game
- Micro-Chess – Chess program by Peter Jennings
- Mastermind – Code-breaking logic game
Sales & Distribution
[edit | edit source]| Package | Contents | Price (1976) | Target Market |
|---|---|---|---|
| Logic Board Only | Assembled PCB with ROMs installed | US$666.66 | Electronics hobbyists |
| Cassette Interface (ACI) | Plug-in card + documentation | US$75 | Data storage capability |
| Complete System | Board + case + PSU + keyboard + ACI | ~US$900–1,200 | Turn-key operation |
Distribution Channels
[edit | edit source]Jobs successfully established Apple I sales through the first generation of computer retailers:[14]
- Byte Shop (Palo Alto, CA) – Primary distributor, ordered first 50 units
- Itty Bitty Machine Company (Evanston, IL) – Early microcomputer retailer
- Data Domain (Bloomington, IN) – Regional computer store
- Computer Mart (New York City) – East Coast distribution
Surviving Examples & Documentation
[edit | edit source]Current research indicates approximately 46-62 verified Apple I computers remain in existence, with documentation maintained by the Apple-1 Registry.[15] Notable auction results demonstrate their historical significance:
| Year | Auction House | Sale Price | Board Details |
|---|---|---|---|
| 2014 | Bonhams | US$905,000 | Working NTI board with documentation |
| 2020 | RR Auction | US$458,711 | Fully functional with original peripherals |
| 2022 | RR Auction | US$677,196 | Production prototype (damaged condition) |
| 2025 | RR Auction | US$375,000 | "Bayville" Apple I (#91 in registry) |
Museum Collections
[edit | edit source]Several world-class institutions preserve Apple I computers for public education:[16]
- Computer History Museum (Mountain View, CA) – NTI board in Revolution exhibit
- National Museum of American History (Washington, DC) – Smithsonian collection
- Science Museum (London, UK) – European computing history display
- Powerhouse Museum (Sydney, AU) – Level 3 iconic exhibition
- Deutsches Museum (Munich, Germany) – Technical history collection
Legacy & Impact
[edit | edit source]The Apple I's significance extends far beyond its ~200-unit production run. It established fundamental principles that defined the personal computer industry:[17]
Technical Innovations
[edit | edit source]- Pre-assembled boards eliminated kit-building complexity
- Integrated video output provided TV-compatible display without additional hardware
- Efficient design minimized chip count through clever engineering
- Expandable architecture supported memory growth from 4KB to 48KB
Business Model Innovation
[edit | edit source]- Complete system concept – moved beyond bare circuit boards to working computers
- Retail distribution – established computer specialty stores as sales channel
- Marketing focus – emphasized simplicity and user-friendliness over technical specifications
- Upgrade path – offered trade-in programs to migrate customers to Apple II
Industry Influence
[edit | edit source]The Apple I directly financed development of the Apple II, which became the foundation of Apple's success and sparked the personal computer revolution of the late 1970s. Its design philosophy of elegant simplicity, powerful yet accessible technology, and focus on the user experience became hallmarks of Apple's approach that continue today.
Replicas & Emulation
[edit | edit source]Modern enthusiasts have created several reproduction projects:
| Project | Type | Features |
|---|---|---|
| Mimeo 1 | Exact reproduction | Period-correct components, original PCB layout |
| Obtronix Apple I | Modern replica | Socketed ICs, modern power supply |
| Briel Replica-1 | Enhanced replica | PS/2 keyboard support, additional features |
| Apple 1emu | Software emulation | Runs Apple I software on modern PCs |
| MESS/MAME | Multi-system emulator | Accurate Apple I hardware simulation |
Technical Documentation
[edit | edit source]Original Apple documentation included:[18]
- Apple-1 Operation Manual – Complete system documentation with schematics
- BASIC Manual – Programming guide for Integer BASIC
- Assembly Instructions – For customers building complete systems
- Cassette Interface Documentation – ACI card installation and operation
References
[edit | edit source]- ↑ Apple-1 Computer, Computer History Museum—link(accessed 2025-01-25)
- ↑ Apple I Microcomputer, National Museum of American History—link(accessed 2025-01-25)
- ↑ The Founding of Apple Computer, Inc., Library of Congress—link(accessed 2025-01-25)
- ↑ Steve Wozniak & Steve Jobs Release the Apple I, History of Information—link(accessed 2025-01-25)
- ↑ Chip Hall of Fame: MOS Technology 6502 Microprocessor, IEEE Spectrum, 2023-12-04—link(accessed 2025-01-25)
- ↑ Steve Wozniak: Inventor and Apple co-founder, UC Berkeley Engineering, 2023-07-27—link(accessed 2025-01-25)
- ↑ Apple is founded by Steve Jobs, Woz and Ron Wayne, Cult of Mac, 2025-04-01—link(accessed 2025-01-25)
- ↑ Steve Jobs and Steve Wozniak, Lemelson-MIT Program—link(accessed 2025-01-25)
- ↑ MOS Technology 6502, C64-Wiki—link(accessed 2025-01-25)
- ↑ The Apple-1, Apple-1 Registry—link(accessed 2025-01-25)
- ↑ Apple-1 Registry—link(accessed 2025-01-25)
- ↑ Apple 1 Registry– WillEgal—link(accessed 2025-01-25)
- ↑ Apple 1 Manual (1976), Internet Archive—link(accessed 2025-01-25)
- ↑ Apple Computer, Inc., Computer History Museum—link(accessed 2025-01-25)
- ↑ Apple-1 Registry List, Apple-1 Registry—link(accessed 2025-01-25)
- ↑ Apple-1 Museums, Apple-1 Registry—link(accessed 2025-01-25)
- ↑ The Apple II, Computer History Museum—link(accessed 2025-01-25)
- ↑ Software and Documents at the Apple-1 Registry, Apple-1 Registry—link(accessed 2025-01-25)