Parity uses the AIL/32 REL105 WR drivers under reference/REL105/RELEASE.105/WR. Pass --drivers to use another copy. LxImage follows DLLLOAD.C when loading objects, pages, zero pages, internal 32-bit fixups, and exported function tables. Unsupported fixups and services fail immediately. UnicornMachine also limits the number of instructions in each call so invalid inputs cannot run forever.
OriginalAdvMusicDriver runs AIL 2.x real-mode music drivers, such as the A214 drivers under reference/A214_D1 and the 1991 drivers of Star Trek: 25th Anniversary, on a 16-bit RealModeMachine; --adv selects one in the CLI. It calls them the way AIL 2.14's call_driver does: through the image's function index, with a far return address and the C word arguments on the stack, a far pointer as offset then segment. Results come back in DX:AX; functions that return a word leave DX undefined, so status reads use AX only.
| Boundary | How the harness handles it |
|---|---|
| Loading | The image must carry Copy after its index word, as AIL_register_driver requires; it is copied to a paragraph at offset zero. The drivers reach their own data through CS overrides, so the harness sets no data segment. |
| Description | describe_driver receives a trap for its timer-rate callback; a call into it fails the run. |
| Initialization | init_driver gets the description table's default I/O, IRQ, DMA and DRQ, as Star Trek: 25th Anniversary passes them. Detection does not run. A nonzero cache size gets a guest cache through define_cache. |
| BIOS data | The CRTC port word at 0463h reads 03D4h, from which the MT-32 drivers derive the retrace port. |
| Hardware ports | The same boundaries as the REL105 drivers, below. |
The A214 drivers produce the same output as their REL105 builds on the generated resources, which checks this machine against the 32-bit one.
| Boundary | How the harness handles it |
|---|---|
| Guest addresses/selectors | Isolated guest allocations and flat selectors support original LES/LDS. No guest pointer crosses into the library API. |
| OPL address/data ports | The harness captures every ordered register write, preserving repetitions, bank identity and both chips on dual OPL2. YAMAHA32.INC:update_reg defines routing. |
| MPU readiness/reset | Deterministic ready/acknowledge replies for MPU40132.INC transport. Channel messages and SysEx bytes execute unchanged. |
| MT-32 retrace wait | Alternating retrace status yields one nominal 14 ms delay per original sysex_wait iteration. Delays are coalesced between complete messages; subsequent message timestamps honor queued waits. |
| PAS shutdown state | The original INT 2F state lookup receives a deterministic neutral state; routing restoration remains observed. |
| PC speaker timer and gate | Port 43h accepts only control word B6h (channel 2, low then high byte, square wave); the two following port 42h bytes form one recorded divisor, repetitions included. Port 61h reads return the last written value; a write may change only bits 0 and 1, and both together, and is recorded as the gate state. |
| Timer service | The harness calls the original exported serve_driver once per service period and records it as serviceTicks in each music result. REL105 builds use 83,330 .NET ticks (QUANT_RATE 120). A real-mode driver uses the period AIL 2.14's AIL_init_driver programs from its declared service rate, 1,000,000 / rate whole microseconds: 2,083 µs for the game's 480 Hz PCSPKR.ADV. No emulated timer hardware is needed. |
| Sequence callbacks | A harness callback observes arguments; optional guest trampolines call the original stop/branch APIs. No sequencer algorithm is replaced. |
| Timbre requests | The test compares the packed patch/bank WORD and the no-request sentinel. The MT-32 source loads a DWORD from the WORD list; adjacent-list bytes above the public patch/bank fields are discarded. |
Bank preloading calls the original installation API for each packed entry in index order before registering and starting the selected sequences. The original driver parses resources and produces the expected musical output. Tests generate their inputs, while the CLI also accepts files and banks supplied by the caller.
MT3232.INC:378–381 pushes EAX and later pops AX while switching patch banks. The WR binary contains 66 58 at loaded offset 0x989, which removes two bytes after a four-byte push and corrupts the saved registers. Depending on the guest addresses, the driver either faults or writes through the wrong pointer.
For MT-32 comparisons, the harness changes those two bytes to 58 90 (POP EAX; NOP) in memory. This keeps instruction offsets and musical behavior intact. A signature check prevents the patch from being applied to an unknown binary, and a separate regression test observes the two-byte imbalance in the unmodified instruction. The file on disk is never changed. MT-32 parity results therefore describe the repaired driver.
OriginalSampleDriver executes the original DMASND32.ASM initialization, VOC parsing, marker search, repeat handling, continuation, rate selection, mixer arithmetic and public controls. The harness resolves each source procedure within its expected scope, where its signature must be unique.
| Boundary | How the harness handles it |
|---|---|
| Detection | The harness reports the device as present at the original detect_device entry because the scenario has already selected its capability. |
| Physical transfer | The harness intercepts DMA_transfer before page fragmentation and records the requested bytes and length. Guest addresses and DMA chunks normalize to one logical sample block. |
| Pause/resume transport | halt_DMA and continue_DMA return at their hardware boundaries. Original public status transitions still execute. |
| Completion interrupt | On whole-block completion, the harness calls the original next_block and process_block routines. |
| Sample rate | The harness executes the original set_sample_rate and interprets the emitted SB time constants, PAS divisors, or Gold frequency bits as exact host frame cadences. The original code chooses among the Gold rates. |
| Mixer | The harness captures SB Pro mixer nibbles, PAS ASCII mixer commands and Gold channel levels after the original arithmetic. Plain SB has speaker enable but no amplitude attenuation. |
| Silence | The harness captures original SB silence commands and frame counts. PAS and Gold execute their original skip branches. |
| Operating-system calls | Deterministic interrupt-vector bookkeeping; PAS state queries and mixer-device open/write/close. Unknown operations fail. |
| Compressed payloads | The harness captures encoded bytes and codec/layout metadata. No hardware ADPCM decoder or software codec is implemented. |
The default generated VOC uses unsigned 8-bit PCM in blocks 1/2. Gold's physical signed-byte preformatting is a transport representation; the logical sink uses the original resource's unsigned bytes and the renderer converts PCM representation. Tests cover raw PCM buffers, extended stereo, silence, markers, repeats and external compressed completion. Physical DMA fragmentation, device startup waits and analog filtering are outside sample-time equality.
build-soundfx-oracle.mjs compiles the A214 SOUNDFX.C file with GCC. Its shim replaces the DOS headers, unavailable AIL and timer calls, diagnostic printing, and DOS EOF marker. The effect logic is unchanged, and its AIL calls still pass through the original music driver. Tests also cover the source's unusual use of a one-based channel directly in the MIDI status nibble.
Parity covers these digital boundaries when both implementations receive the same inputs and timing. It includes repeated OPL writes, speaker timer reloads and gate writes, message order, voice behavior, sample restarts, completion, and rate and mixer choices. It does not cover physical port timing, analog response, application filters, MT-32 synthesis, external decoding, or the accuracy of NukedOPL3Sharp itself.