diff --git a/docs/architecture.md b/docs/architecture.md
index 2e5ac01..1c801a3 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -49,15 +49,16 @@ HAL writes straight to stdout.
 | INPUT/LINE INPUT | `input.c` | BINTRP.ASM |
 | Sound engine | `sound.c` | — |
 | Virtual memory (PEEK/POKE) | `virmem.c` | — |
+| Hardware I/O ports | `portio.c` | — |
 | Platform abstraction | `hal_posix.c` | OEM*.ASM |
 
 ## Source Layout
 
 ```
-src/         — core interpreter (21 files)
-include/     — headers (13 files)
+src/         — core interpreter (22 files)
+include/     — headers (14 files)
 platform/    — HAL backends (1 file)
-tests/       — 66 automated test programs, 4 classic interactive programs, compat harness
+tests/       — 70 automated test programs, 4 classic interactive programs, compat harness
 docs/        — Sphinx documentation
 ```
 
diff --git a/docs/development.md b/docs/development.md
index 649450a..3bf3556 100644
--- a/docs/development.md
+++ b/docs/development.md
@@ -18,10 +18,11 @@
 | 0.12.0 | | BSAVE/BLOAD, TUI ANSI 16-color rendering, CGA graphics framebuffer PEEK/POKE, keyboard shift flags |
 | 0.13.0 | | VIEW/WINDOW/PALETTE graphics, PMAP function, MBF float format for CVS/CVD/MKS$/MKD$ |
 | 0.14.0 | | MBF binary file compatibility (IEEE↔MBF at save/load boundary), fix binary loader null-byte truncation, fix DRAW M/S/A bugs, add TA/=var;/X substring |
+| 0.15.0 | | Hardware I/O simulator: OUT/INP/WAIT/MOTOR statements, port emulation (8253 PIT, PPI speaker, CGA mode/color, COM1, game port), continuous tone via PulseAudio |
 
 ## Tests
 
-68 test programs in `tests/programs/`, plus 4 classic interactive programs in
+70 test programs in `tests/programs/`, plus 4 classic interactive programs in
 `tests/classic/` (Hamurabi, Lunar Lander, Gunner, Diamond from David Ahl's
 *BASIC Computer Games*).
 
@@ -31,10 +32,10 @@ Run the full automated suite:
 bash tests/run_tests.sh
 ```
 
-Each test has a 5-second timeout. 62 tests have `.expected` golden files
-for output regression detection. Three timing-dependent tests (datetime,
-on_timer, timer_stop) and one visual test (color_test) run without golden
-comparison.
+Each test has a 5-second timeout. 65 tests have `.expected` golden files
+for output regression detection. Tests without golden comparison: datetime,
+on_timer, timer_stop (timing-dependent), color_test (visual), play_music
+(audio duration).
 
 ### Compatibility Testing
 
diff --git a/docs/index.md b/docs/index.md
index 8c419ed..1cfb5c3 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -19,12 +19,15 @@ version is structured as modular C suitable for new feature development.
 - **INKEY$ extended keys** — arrow keys, F-keys, and navigation keys return proper
   `CHR$(0)` + scan code two-byte sequences
 - **Sixel graphics** — `SCREEN 1`/`SCREEN 2` rendering in compatible terminals
-- **Sound** — `SOUND`, `BEEP`, `PLAY` (MML) via PulseAudio
+- **Sound** — `SOUND`, `BEEP`, `PLAY` (MML) via PulseAudio, plus continuous tone
+  via `OUT` (8253 PIT / PPI speaker emulation)
+- **Hardware I/O** — `OUT`, `INP`, `WAIT` port emulation (PIT, PPI, CGA, COM1,
+  game port) for classic programs that drive hardware directly
 - **Full file I/O** — sequential, random-access, SAVE/LOAD/MERGE/CHAIN/COMMON
 - **Printer output** — `LPRINT`/`LLIST` to file or real hardware via `--lpt`
 - **Classic programs** — Hamurabi, Lunar Lander, Gunner, and Diamond from
   David Ahl's *BASIC Computer Games* (1978) run out of the box
-- **66 test programs** with golden-file regression testing and DOSBox-X
+- **70 test programs** with golden-file regression testing and DOSBox-X
   compatibility testing against real GWBASIC.EXE
 - **MIT License**
 
diff --git a/docs/language-reference.md b/docs/language-reference.md
index bf848ed..d066981 100644
--- a/docs/language-reference.md
+++ b/docs/language-reference.md
@@ -60,6 +60,7 @@ type suffixes (`%`, `!`, `#`)
 | Graphics | `PSET`, `PRESET`, `LINE`, `CIRCLE`, `DRAW`, `PAINT`, `GET`, `PUT`, `VIEW`, `WINDOW`, `PALETTE`, `PMAP` |
 | Sound | `SOUND`, `BEEP`, `PLAY` (MML parser, PulseAudio backend) |
 | Memory | `DEF SEG`, `PEEK`, `POKE`, `BSAVE`, `BLOAD` |
+| Hardware I/O | `OUT`, `INP`, `WAIT`, `MOTOR`, `STICK`, `STRIG` |
 | Misc | `KEY`, `TRON`/`TROFF`, `OPTION BASE`, `MID$` assignment |
 | System | `SYSTEM` |
 
@@ -222,6 +223,42 @@ The file format is compatible with the original GW-BASIC: byte 0 = `0xFD`,
 bytes 1-2 = segment (LE), bytes 3-4 = offset (LE), bytes 5-6 = length (LE),
 followed by the raw data bytes.
 
+## Hardware I/O (OUT / INP / WAIT)
+
+`OUT`, `INP`, and `WAIT` provide access to emulated IBM PC I/O ports, enabling
+classic programs that drive hardware directly — speaker tones via the 8253 PIT,
+CGA palette tricks, and serial port polling.
+
+```
+OUT &H43, &HB6              ' PIT channel 2: lobyte/hibyte, mode 3
+OUT &H42, &HD3 : OUT &H42, &H04   ' set frequency divisor (1235 → 966 Hz)
+OUT &H61, INP(&H61) OR 3    ' speaker on
+OUT &H61, INP(&H61) AND &HFC ' speaker off
+```
+
+### Emulated Ports
+
+| Port | Device | Behavior |
+|------|--------|----------|
+| `&H42`–`&H43` | 8253 PIT channel 2 | Speaker frequency divisor (1193180 / divisor Hz) |
+| `&H61` | PPI Port B | Bits 0–1 control speaker; both set = tone on, either clear = off |
+| `&H3D8` | CGA mode control | Mode register; writes with changed mode bits trigger `SCREEN` changes |
+| `&H3D9` | CGA color select | Background color (bits 0–3) and palette select (bit 5) |
+| `&H201` | Game port | Returns `&HF0` (no joystick connected) |
+| `&H3F8`–`&H3FE` | COM1 serial | Minimal stub; LSR (`&H3FD`) returns `&H60` (transmitter ready) |
+| Default | — | Reads return `&HFF` (floating bus), writes silently discarded |
+
+### Related Functions
+
+- `INP(port)` — read a byte from an I/O port
+- `STICK(n)` — joystick axis position (returns 128 = center, n = 0–3)
+- `STRIG(n)` — joystick button state (returns 0 = not pressed)
+- `WAIT port, mask [, xor_mask]` — busy-wait until `(INP(port) XOR xor_mask) AND mask` is nonzero; Ctrl+C breaks out
+- `MOTOR [n]` — accepted and silently ignored (cassette motor control)
+
+When the PPI speaker bits are set, the PIT frequency divisor is used to
+generate a continuous tone via PulseAudio (same backend as `SOUND` / `PLAY`).
+
 ## Sound
 
 - `SOUND frequency, duration` — play a tone (frequency in Hz, duration in clock ticks)
diff --git a/docs/roadmap.md b/docs/roadmap.md
index b4c12f1..f23b2dc 100644
--- a/docs/roadmap.md
+++ b/docs/roadmap.md
@@ -8,35 +8,21 @@
   But we've come this far, so why not?  Likely approach: translate the token
   stream to C and lean on GCC/Clang for the heavy lifting.
 
+## Completed
+
+### Hardware I/O Simulator (v0.15.0)
+
+Implemented in `portio.c` / `portio.h` following the `virmem.c` dispatch
+pattern.  Emulates 8253 PIT channel 2 (speaker frequency), PPI port B
+(speaker on/off with continuous tone via PulseAudio), CGA mode/color
+registers, game port (joystick stub), and COM1 serial (transmitter-ready
+stub).  Default: reads return 0xFF (floating bus), writes discarded.
+
+Statements: `OUT`, `WAIT`, `MOTOR`.  Functions: `INP()`, `STICK()`, `STRIG()`.
+
 ## Next Up
 
-### Hardware I/O Simulator
-
-An optional emulation layer for `OUT`, `INP`, `WAIT`, `MOTOR`, and friends,
-following the established `virmem.c` dispatch-by-address pattern.
-
-**New module:** `portio.c` / `portio.h` with `portio_inp(port)` /
-`portio_out(port, value)` dispatch.
-
-**Priority ports:**
-
-| Port | Device | Emulation |
-|------|--------|-----------|
-| 0x42–0x43 | 8253 PIT channel 2 | Speaker frequency divisor (1193180 / divisor Hz) |
-| 0x61 | PPI Port B | Speaker on/off (bits 0–1), routes to `snd_start_continuous()` / `snd_stop_continuous()` |
-| 0x3D8 | CGA mode control | Mode register storage, feeds `gfx_init()` |
-| 0x3D9 | CGA color select | Palette/background bits, feeds `gfx_palette_set()` |
-| 0x201 | Game port | Joystick stub (returns 0xF0 = no buttons) |
-| 0x3F8–0x3FE | COM1 serial | Minimal stub (LSR reports transmitter ready to prevent spin loops) |
-| Default | — | Reads return 0xFF (floating bus), writes silently discarded |
-
-**Statement/function changes:**
-
-- `OUT port, value` → `portio_out(port, value)`
-- `WAIT port, mask [, xor_mask]` → busy loop with `portio_inp()`, break check, timeout
-- `MOTOR` → accept and silently ignore
-- `INP(port)` → `portio_inp(port)` (currently returns 0)
-- `STICK(n)` / `STRIG(n)` → joystick state from port 0x201
+*(Looking for the next major feature — see IDE and Notebook Integration below.)*
 
 ## IDE and Notebook Integration
 
diff --git a/include/gwbasic.h b/include/gwbasic.h
index 018f366..5fbc149 100644
--- a/include/gwbasic.h
+++ b/include/gwbasic.h
@@ -10,7 +10,7 @@
 #include "gw_math.h"
 #include "strings.h"
 
-#define GW_VERSION "0.14.0"
+#define GW_VERSION "0.15.0"
 #define GW_BANNER "GW-BASIC " GW_VERSION
 
 /* Tokenizer */