Changelog

All notable changes to zen80 are documented in this file.

The format is based on Keep a Changelog.

0.1.0 - 2026-06-26

First versioned release. Establishes the release-hygiene baseline (VERSION file, pkg/version package, syncver.sh, release.sh, this changelog) for the existing zen80 codebase.

Emulator core

• Instruction-stepped Z80 CPU core with full documented instruction set: main, CB-prefixed, ED-prefixed, DD/FD-prefixed (IX/IY), and DDCB/FDCB indexed bit operations.
• Accurate flag handling including the undocumented X and Y flags, and the internal WZ (MEMPTR) register.
• Interrupt support: NMI (edge-triggered) and maskable interrupts in modes 0, 1, and 2, with a two-phase Mode 0 instruction-injection buffer and an optional InterruptController interface for vector and Mode 0 supply.
• Correct R-register refresh increment on the M1 cycle.

Memory and I/O

• memory package: RAM (64 KB), ROM, and MappedMemory (ROM-low / RAM-high with power-of-two ROM mirroring).
• io package: NullIO, SimpleIO (256-port array), and MappedIO (per-port and 8-bit-decode fallback handlers).

System layer

• system package providing a ZX Spectrum system: 48 KB memory map, ULA keyboard/border/speaker I/O, frame timing, and vertical-blank interrupt generation.

Tooling

• pkg/version package exposing the Version constant, kept in sync with the root VERSION file via syncver.sh.
• release.sh single-pass release preparation: version validation, CHANGELOG check, version sync, build, single test pass with coverage, a version-consistency check, and a binary-free, artifact-free checkpoint zip.

Documentation

• runtest.sh now skips the ZEXDOC/ZEXALL exercisers by default (they have their own runners and take minutes); pass --zex to include them.
• Expanded the README testing section to document the three test tiers (fast unit tests, the ROM-backed opcode-coverage test, and the ZEXDOC/ZEXALL conformance exercisers), including the environment variables that gate the exercisers and why go test alone triggers a long run.