From Brian Willoughby Sent Thu, Jun 7th 2018, 06:51
On Jun 4, 2018, at 2:57 PM, Kenny Balys <xxxxx@xxxxxxxx.xxx> wrote: > Perhaps one could say the transition to interpolation happened with = the release of the Ensoniq Mirage in 1984. It was probably cheaper to = let the CPU do the work than have a cascade of logic dividing down clock = frequencies. It=E2=80=99s a little misleading to describe the Mirage this way, but = you=E2=80=99re probably correct that the Mirage changed everything. The Mirage operating system runs on a 6809, which is a fairly standard = 8-bit processor. But that little processor hardly processes samples on = its own. Ensoniq also designed custom ASIC chips, although I=E2=80=99m = not sure about the names. The Mirage FAQ mentions the Q-Chip while the = Wikipedia page mentions the Digital Oscillator Chip (Ensoniq ES5503 DOC) = that later appeared in the Apple //gs. These custom chips have way more = than "a cascade of logic dividing down clock frequencies,=E2=80=9D and = they=E2=80=99re the real reason that the Mirage was so affordable.=20 The DOC was designed by Robert Yannes, who had designed the SID chip. = Ensoniq followed up with the ESP (Ensoniq Signal Processor). At one = point, IBM was in discussions with Ensoniq about licensing the ESP as a = future IBM DSP, but the deal fell through. These were separate from the = required DAC chips. Basically, the experience of making affordable home computers like the = Commodore-64 are what allowed us to enjoy a serious advancement in = sampling sound. I=E2=80=99m a bit more familiar with the ESP, because it is available on = the Ensoniq Soundscape cards and was fairly well documented. Some = sources refer to it as having an instruction set, but I don=E2=80=99t = know whether that was ever exposed to customers. The Soundscape allowed = access to registers that controlled various aspects of sampled voices, = but I don=E2=80=99t recall an assembler or compiler. I have the = documentation around here somewhere, but I=E2=80=99m going from memory = on this. The modern equivalent of the Mirage would probably be based on an FPGA = plus a general purpose CPU for the main operating system. The FPGA would = be able to handle the dense logic that used to require an ASIC. Brian Willoughby Sound Consulting