MicroBasement Collection Timeline: 1970s–1990s Microcomputers

This timeline organizes the MicroBasement collection chronologically by introduction year (or major release), showing the progression of microcomputing from the first DIY kits and trainers to powerful multimedia laptops. Each entry includes a basic overview of features in bullet form and what it added to the era. The collection spans the birth of the microprocessor to the dawn of portable productivity, with many machines reflecting key innovations in the hobbyist and early personal computing worlds.

1970s – The Dawn of Microcomputing & Trainers

• Busicom 141-PF (1971)
  • First commercial product with a microprocessor (Intel 4004)
  • Desktop printing calculator with nixie tubes and thermal printer
  • 4-bit CPU, basic arithmetic functions
  • Milestone: Marks the birth of the microprocessor era
• Mark-8 Minicomputer (1974, published by Jonathan Titus)
  • Intel 8008 CPU
  • 256 bytes RAM (expandable)
  • DIY from Radio-Electronics schematics; 6 boards, hex keypad/LEDs
  • Milestone: First major publication build-your-own computer; sparked homebuilt micros
• Scelbi 8B (1974)
  • Intel 8008 CPU
  • 1 KB RAM
  • First commercially available microcomputer kit
  • Milestone: Early hobbyist kit with hex keypad and LED display
• MIL MOD 8 (1974)
  • Intel 8008-based trainer/kit
  • Basic educational microcomputer
  • Milestone: Niche trainer for learning 8008 architecture
• Altair 8800 (1975)
  • Intel 8080 CPU
  • 256 bytes RAM (expandable)
  • S-100 bus, front panel switches/LEDs
  • Milestone: First popular kit computer; sparked Microsoft BASIC
• IMSAI 8080 (1975)
  • Intel 8080 CPU
  • Improved S-100 bus
  • Front panel, better build quality than Altair
  • Milestone: Commercial rival to Altair; widely used in early businesses
• MOS KIM-1 (1976)
  • MOS 6502 CPU
  • 1 KB RAM, 2 KB ROM monitor
  • Hex keypad, 6-digit LED, cassette I/O
  • Milestone: Iconic single-board trainer; inspired Apple I
• Ferguson BigBoard I (1977)
  • Z80 CPU
  • 64 KB RAM, CP/M compatible
  • S-100 compatible single-board computer
  • Milestone: Early Z80 kit for CP/M enthusiasts
• Radio Shack TRS-80 Model I Level II (1977)
  • Z80 CPU @ 1.77 MHz
  • 4–48 KB RAM
  • Level II BASIC in ROM, cassette storage
  • Milestone: Mass-market success; huge software library
• Commodore PET 2001 (1977)
  • MOS 6502 CPU @ 1 MHz
  • 4–32 KB RAM
  • Built-in monitor, cassette, PET BASIC
  • Milestone: All-in-one home/business computer
• Apple II Plus (1979)
  • MOS 6502 CPU @ 1 MHz
  • 16–128 KB RAM
  • Color graphics, 8 slots, Disk II floppy
  • Milestone: Expandable, huge software base; education/gaming king
• Atari 400 (1979)
  • MOS 6502 CPU @ 1.79 MHz
  • 8–48 KB RAM
  • Custom ANTIC/GTIA/POKEY chips: 256 colors, 4-channel sound
  • Milestone: Arcade-quality graphics/sound in a home computer
• Commodore VIC-20 (1980)
  • MOS 6502 CPU @ 1 MHz
  • 5 KB RAM
  • Color graphics, sound, cartridge slot
  • Milestone: Affordable entry-level computer; millions sold
• Elenco 6802D5 Microcomputer Trainer (early 1980s)
  • Motorola 6802 CPU
  • 1 KB RAM, 2 KB ROM monitor
  • Hex keypad, LED display, breadboard area
  • Milestone: Vocational trainer for 6800/6802 family
• Radio Shack TRS-80 Color Computer 128K (CoCo 3, 1986)
  • Motorola 6809E CPU @ 1.79 MHz
  • 128 KB RAM
  • GIME chip: 256 colors, 640x192 graphics, 6-channel sound
  • Milestone: Advanced 8-bit with OS-9 multitasking
• Sinclair ZX80 (1980)
  • Z80 CPU @ 3.25 MHz
  • 1 KB RAM
  • 1 KB ROM BASIC, membrane keyboard
  • Milestone: Ultra-cheap (~$200) entry-level computer
• Sinclair ZX81 (1981)
  • Z80 CPU @ 3.25 MHz
  • 1 KB RAM (16 KB expandable)
  • Improved ZX80; 1 KB RAM, better BASIC
  • Milestone: Sold millions; hobbyist favorite
• Sinclair ZX Spectrum+ (1984)
  • Z80 CPU @ 3.5 MHz
  • 48 KB RAM
  • Improved keyboard, RGB output, 256x192 graphics
  • Milestone: UK gaming icon; massive software library
• Sharp PC-4500 Laptop (1987)
  • 8088-compatible CPU
  • 256 KB RAM (up to 640 KB)
  • Dual 3.5" 720 KB floppies, 8" mono LCD
  • Milestone: Your first laptop; dual-floppy portability pioneer

1980s–1990s – IBM PC Era & Portables

• IBM PC 5150 (1981)
  • Intel 8088 CPU @ 4.77 MHz
  • 16–640 KB RAM
  • Open architecture, CGA graphics, PC-DOS
  • Milestone: Defined IBM PC compatibles; business standard
• IBM Portable PC 5155 (1984)
  • 8088 CPU
  • 256 KB RAM
  • Built-in 9" mono CRT, dual 5.25" floppies
  • Milestone: Early portable IBM compatible
• IBM XT 5160 (1983)
  • 8088 CPU @ 4.77 MHz
  • 128–640 KB RAM
  • Built-in hard drive (10 MB), 8 slots
  • Milestone: First IBM with hard drive
• IBM AT 5170 (1984)
  • Intel 80286 CPU @ 6–8 MHz
  • 256 KB–16 MB RAM
  • 1.2 MB floppy, 20–40 MB HDD, AT keyboard
  • Milestone: 16-bit performance; protected mode
• Apple Macintosh Plus (1986)
  • Motorola 68000 CPU @ 8 MHz
  • 1 MB RAM
  • 800 KB floppy, SCSI port, GUI (Mac OS)
  • Milestone: Improved Mac with expandability
• Micron Millennia Transport Laptop (1995–1996)
  • Pentium 75–166 MHz
  • 8–64 MB RAM
  • 11.3"/12.1" color LCD, CD-ROM, Sound Blaster
  • Milestone: Your first Pentium multimedia laptop

Summary & Progression

The collection traces microcomputing from microprocessor birth (Busicom 141-PF) ? DIY trainers (Mark-8, 6802D5) ? 8-bit home computers (Atari 400, TRS-80, Sinclair) ? IBM PC compatibles ? early portables (Sharp PC-4500) ? multimedia laptops (Micron Transport). It shows the rapid evolution from kits and limited RAM to powerful, portable machines with color and sound.

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