Casio SF-4000 Digital Diary — one of the first mass-market electronic organizers (predecessor to modern smartphones and PDAs), dating back to the period of 1988–1991.

Casio SF-4000 Digital Diary — one of the first mass-market electronic organizers (predecessor to modern smartphones and PDAs), dating back to the period of 1988–1991.

Background: The SF-4000 model was introduced in 1988. This was the "golden era" of electronic notebooks, when they were considered a status business accessory.

Condition: The body and box are in excellent "Near Mint" condition. Original instructions and packaging are included.

Features: Telephone directory (up to 1,500 numbers), notepad, calendar, task planner, and a 10-digit calculator.

Memory: 32 KB (approx. 30,000 characters), which was an impressive volume for 1988. The memory has not been reset.

Display: 6-line monochrome LCD screen. It is ultra-high contrast for its time.

Power: Operates on 3 CR2025 lithium batteries (new ones installed).

Product Quality:

• Build: Exceptional. High-quality matte plastic that does not yellow over time.
• Keyboard: Membrane type, but with a very clear tactile response.
• Cosmetics: Only minimal signs of age are visible; no deep scratches or chips. The "DIGITAL DIARY" and "CASIO" inscriptions are not worn off.
• Technical State: The screen works, characters are sharp, and no dead pixels are visible. The "Memory contents were broken" error is a standard status (reporting empty memory), not a defect.

A perfectly preserved specimen of late-80s Japanese technology.