kz80_calc

A VisiCalc-style spreadsheet for the Z80 processor, targeting the RetroShield platform.

Features

• 16×64 cell grid (columns A-P, rows 1-64)
• 16-bit integer values
• Formula support: =A1+B2, =C3*5, =SUM(A1:A10)
• Arrow key navigation
• Automatic recalculation
• Fits in 8KB ROM / 6KB RAM

Building

cargo build --release
./target/release/kz80_calc -o spreadsheet.bin

Usage

Run with the RetroShield emulator:

retroshield spreadsheet.bin

Keys

• Arrow keys: Navigate cells
• Enter: Edit cell
• Escape: Cancel edit
• Letters/numbers: Enter values or formulas
• =: Start formula entry

Formulas

=A1+B2      Addition
=A1-B2      Subtraction
=A1*B2      Multiplication
=A1/B2      Division
=SUM(A1:A5) Sum of range

Memory Layout

ROM (8KB):
  0x0000-0x00FF  Startup, vectors
  0x0100-0x1FFF  Spreadsheet engine

RAM (6KB):
  0x2000-0x2FFF  Cell data (4KB = 1024 cells)
  0x3000-0x35FF  Formula buffer, parse state
  0x3600-0x37FF  Display buffer, stack

Inspiration

Inspired by VisiCalc (1979), the original "killer app" that launched the personal computer revolution.

License

BSD 3-Clause License