v0.3.0

Highlights

• Directory-mounted floppy disks — point a drive at a plain directory and
  it is served as a live floppy: MZF files appear as a Disk BASIC disk, or
  any files as a LEC CP/M data disk. Fully writable: guest saves, deletes and
  renames become real files; formatting the disk clears the directory.
• Complete MZ-800 sound (Deluxe board) — the 8253 beeper joins the
  existing SN76489 PSG emulation, covering monitor beeps, S-BASIC MUSIC,
  MZ-700 melody, and 1-bit "beeper engine" game music with microsecond
  event timing; both chips mix into the I2S output.
• Paged RAM disk (MZ-1R18 style) — a new ramdisk device (Deluxe
  board) with 64 KB page switching and full 16-bit addressing, backed by
  Pico RAM or by an image file for persistent content.

Added

• Directory-mounted floppy (image_disk<N>= a directory; fs_disk<N>=basic|cpm
  or auto-detect). Honest free-space reporting and write-error propagation to
  the guest; not bootable by design.
• ctc device: the 8253 beeper, fed from both the I/O-mapped ports and the
  memory-mapped E00x path (captured with a hardware memory-write snoop and
  ~1 µs timestamps), with mode-aware GATE0 and bank-switch tracking. The
  I2S path was reworked into a multi-source mixer so it plays alongside
  the existing psg (SN76489) device, with matched volume defaults.
• ramdisk device: MZ-1R18-style paged RAM disk with full 16-bit
  addressing, RAM- or file-backed (Deluxe board only — Frugal cannot
  capture the 16-bit positioning; use pico_rd there).
• FDC: track formatting (WRITE TRACK), READ TRACK, multi-sector transfers,
  per-drive write protection (write_protected<N>); formatting an empty
  image file creates a usable disk.
• Writable directory-mounted Quick Disks: saving from the MZ-800 creates real
  .mzf files; QD formatting clears the directory.
• Soft Z80 reset: the reset button re-initializes devices in place — WiFi
  association and audio survive, explorer-mounted images revert to the ini
  configuration. Press twice within a few seconds for a full restart.
• Minimal HTTP status API on Pico W builds (port 8080): /api/ping and
  /api/status liveness/uptime checks; groundwork for future remote
  control.
• 16-bit I/O addressing on Deluxe for reads and writes (high address byte
  available to devices).
• sd:/mzpico.ini is used when present; internal flash is the fallback.
• Board-aware configuration: one ini works on every board — sections for
  devices the board cannot support (e.g. sound on Frugal) are skipped.
• Out-of-RAM resilience: a device whose buffers do not fit is skipped with
  the rest of the system booting normally, instead of halting.
• Commented default mzpico.ini written on flash format: every device
  section present, common options shown, pico_rd file-backed.

Fixed

• Power-up boot race: single-pass cold boot (the historic double-reboot
  workaround burned ~100 ms of a ~180 ms budget); 16 MB builds additionally
  run QSPI flash at a clone-safe 45 MHz.
• Flash filesystem hardening: double-buffered metadata (a power cut during a
  write can no longer lose the volume), freed pages quarantined until
  metadata is persisted (fixes a total-loss scenario after over-filling the
  volume), no auto-format of damaged volumes, full-disk overflow guard,
  and much faster device-side formatting.
• Cloud commands run asynchronously on core 0: no more multi-second bus
  holds or frozen audio during cloud transfers; WiFi reconnect backoff no
  longer blocks audio.
• Frugal boards: write data is captured in the PIO at /WR time, closing a
  sampling race under load.
• Quick Disk: save trailer format, end-of-media reads, write-protect
  reporting.
• FDC: write durability (per-sector sync), disk-swap teardown, empty-drive
  crashes.

Changed

• Build hardened against z88dk toolchain drift (the snap auto-updates; a
  z88dk behavior change once broke the explorer's execute key in fresh
  source builds — release binaries were unaffected).

• Default mzpico.ini now includes the sound devices and ships pico_rd
  file-backed (image=flash:/pico_rd.img) so the default set fits Pico W
  RAM.

• README substantially expanded: board-support matrix, complete
  all-devices/all-options example configuration, per-device references for
  pico_rd/pico_mgr, RAM budget guidance, directory-mount documentation.

Migration notes

• Beeper: existing mzpico.ini files predate the [ctc] section — add
  [ctc] (Deluxe) to get beeper sound. The new default ini includes it, but
  the default is only written when the flash is formatted.
• Flash volumes: volumes created by v0.2.0 or older keep working but
  lack the new power-loss protection. Back up the files and reformat with
  the mzpico_format UF2 to upgrade.
• Pico W RAM: if you use pico_rd on a W build, prefer a file-backed
  image (image=...) — a RAM-backed 64 KB pico_rd plus the full default
  device set exceeds the W heap.