I had to read the Music V manual, but I finally found the bit-depth used for the examples in Mathews’ The Technology of Computer.  12-bit, just as I suspected. According the manual, the digital-analog-converters (DAC) at Bell Telephone Laboratories (BTL) operated with 12-bit samples. (pg. 168)

I don’t recall running across a 12-bit audio-file, ever. They just don’t make them like they used.  I don’t even think Csound natively supports outputting a 12-bit file. However, it does allow us to easily simulate it with the 0dbfs opcode.

I rewrote part the CSD file from part 1 to better preserve the the original structure of the Music V example. Instead of rescaling the audio output signal of instr 1 by a factor of 16, I elminated this multiplier, and set the global dynamic range to 12-bit with 0dbfs = 2048. Original Music V amplitudes can now be used without modyifing the values or making unnecessaring changes to instrument translations. Here is the new CSD: Csound_Vs_MusicV_pt2.csd

Csound makes changing the dynamic range easy. In fact, almost all modern software allows users to choose from a list of several bit depths. Music V, not so much. When Music V was installed at a new installation, parts of the program would have to be coded, in assembly and/or Fortran, specifically for that particular system. Including the dynamic range. In theory, other computer facilities might have used a different dynamic range other than 12-bit, based on the hardware they had on site.

One interesting bit of information I discovered is something that could be considered a precursor to the modern audio buffer.

The General Electric GE645 computer at BTL used a 36-bit word length machine. In BTL’s particular setup, Music V would have to create 3 samples and collect them into a single 36-bit word before sending this word to the digital reel-to-reel. This isn’t too unlike the latency buffer found in programs such as Ableton Live, Max, Reaktor, etc., where n amount of samples are collected into a temporary buffer before sending the buffer to the DAC.