Firmware emulation

Reproducing an old instrument by simulating its computer and running its original ROM, rather than by modelling how it sounded. The emulator implements the CPU, the sound chips, the timers and the memory map; the instrument's own code then boots and runs on top of that, unmodified. This is how VES plays a Yamaha DX100 or a Casio CZ-101, using an embedded MAME.

It sits opposite the technique the rest of this spoke assumes.

Two ways to rebuild an instrument in software

• Virtual analog / physical modelling rebuilds the behaviour. Someone studies the circuit, derives or fits a difference equation, and writes DSP that produces a similar signal — the Moog ladder derivation is the corpus's worked example. The output is an approximation whose fidelity is an open empirical question, which is exactly the analog-vs-digital argument.
• Firmware emulation rebuilds the machine. Nobody models the sound at all. If the CPU, the sound chip and the timing are right, the sound is whatever the original code computes, because it is the original code computing it.

The difference matters most in what each can reach. Firmware emulation is nearly exact for an instrument whose voice is digital — FM, phase distortion, PCM playback, sample replay — because there the sound genuinely is computation and reproducing the computation reproduces the sound. It has much less to say about an analog voice path, where the interesting behaviour is in transistors and capacitors that no ROM describes. VES's machine list shows the constraint plainly: about 45 instruments, almost all digital, with the Prophet-5 and Six-Trak as awkward exceptions.

What it costs

• You need the ROM. The firmware is copyrighted and usually still owned by a live company, so projects distribute the emulator and not the thing it emulates. VES excludes ROMs, firmware and NVRAM from source control and tells the user to obtain them; the legally clean product is one that does not work until the user solves the hard problem themselves.
• Accuracy is inherited, not authored. The instrument sounds as good as the upstream driver, and the project shipping the plug-in usually cannot improve it. VES says so directly: availability and completeness "depend on the current state of the corresponding MAME drivers."
• The original interface comes along. Emulating a machine gives you its front panel, including instruments that predate MIDI. VES has to add "virtual MIDI retrofit" paths so a Prophet-5, a LinnDrum or an Oberheim DMX can be driven from a DAW at all.

Why this changes the recreation spectrum

vintage-recreation runs from part-for-part copy through budget clone and architecture homage down to software emulation, with fidelity traded against price at every step. Firmware emulation does not sit on that line. It is not a copy of the circuit and not an approximation of the sound; for a digital instrument it is closer to the same instrument on different hardware, at a price nearer the free end than the €10,000 one. What it costs instead is legality and completeness rather than fidelity, which is a different currency than the rest of the spectrum trades in.

Related

vintage-emulator-studio · mame · vintage-recreation · analog-vs-digital · synthesizer · sampler · synthesis