User Program Memory Vs. Total Program Memory Confusion

[mgiuliani]

I am working with a PIC24FJ256GA606. 256KB of program memory. In CCS Compiler, it says ROM space is 176KB, which aligns with "Program Memory Upper Boundary" listed in its datasheet on page 54: https://ww1.microchip.com/downloads/en/DeviceDoc/PIC24FJ1024GA610-GB610-Family-Data-Sheet-DS30010074G.pdf. Although the datasheet seems to have a typo where all of the decimal counterparts for the memory sizes are half of the hex values.

They also have a diagram showing unimplemented memory, Executive Code Memory, Customer OTP memory, etc. Is everything beyond "User Flash Program Memory" where the other 80KB of program memory is going or is there some other explanation? Kind of confused about how this works or how to explain it to other people.

[Ttelmah]

Basically forget it...

The 'executive code memory', is not something you can ever use. It is
described in the chip's programming specification sheet.It is where code
used by the ICSP can be put. It is only used by the actual device debuggers
and programmers.
The Hex values give the byte addresses. The decimal values are in words.
The memory is treated as word addressable blocks, but the physical address
(which the hex value gives), is in bytes.

Now all the PIC24/30/33 chips, the memory only has three bytes out of
every four addresses implemented. So: