Hi Mark --
Sorry if this message sounds pedantic. Can't find the right tone...
Yamaha confuses people when they speak of "user memory," "internal memory," etc. They are usually referring to
logical, user visible storage.
When getting down to the hardware level, there are many different
physical memory units. since we're not discussing fairy dust or magic, the logical storage must be assigned to one or more physical memory units. And, of course, the physical memory units themselves may be composed of multiple integrated circuits.
The other dimension is "what communicates to what." Memory is passive and needs a processor to initiate reads and writes. At the physical level, a memory unit essentially belongs to a single processing unit.
The CPU/SWP70 is not exactly analogous to host CPU plus GPU. Graphics memory is shared between CPU and GPU. The SWP70 does not share its waveform memory with anybody -- it's dedicated to the tone generator. That's why installing a pack is kind of slow and complicated, and why a Genos reboot is required.
Staying with Genos, Genos has two SWP70 tone generators: one handles factory presets and the other handles user expansion voices. The factory SWP70 has 4GBytes of flash memory while the expansion flash memory has 1GB of flash memory. That's
physical memory. Yamaha boosted the effective capacity to 3GB expansion through compression.
The SWP70s also have DSP RAM. As a user, you never know about this memory. It's scratchpad memory for DSP effects. Physically, the DSP RAM is completely separate and independent from the waveform memory, and communicates with only its parent SWP70.
The host CPU has two kinds of memory (as determined by its bus interfaces): 1GB of working RAM on the CPU memory bus (EMIF) and two embedded eMMC memory devices that act like solid state storage drives (MMC0 and MMC1). As far as a user is concerned, the user never sees the 4GB eMMC drive (MMC0) just like you don't see the DSP RAM; it's hidden. The MMC0 drive contains the Linux operating system kernel and the root file system.
The user sees only part of the second 64GB eMMC drive (MMC1). The user sees the
logical storage which Yamaha calls "Internal memory" or "USER drive." What's in the remaining 6GB? I don't know -- Yamaha haven't left any clues.
Hope this helps with respect to Genos -- pj