I completed a university course called "Microcontrollers: Programming and Interfacing" in which we studied the PIC24F microcontroller, specifically PIC24FJ128GA010, as a computer engineering course. My CS counterparts did a course studying the 8086 microprocessors. From what I studied the PIC24 has 16 working registers for data manipulation and other purposes and those registers were located in the data memory (SFR area). From what I know, the 8086, which is a CPU, has general-purpose registers such as eax, ebx, ecx, etc. From what I understand the 8086 GPRs are somewhat similar to the working registers of the PIC, but my confusion is that why are the working registers located at the data memory and not in the PIC's CPU similar to the 8086? Are there GPRs in the PIC's CPU that are distinct from the working registers? And if not, is this one of the distinctions between a microcontroller and a microprocessor? From my understanding, a microprocessor is essentially a CPU on chip only, whereas a microcontroller has a CPU, memory, and I/O in a single chip. Please elaborate if it appears that I'm missing something.
Your understanding of the fundamental difference between a microcontroller and a microprocessor is spot-on. A microprocessor, like the Intel 8086, is essentially the core processing unit of a computer. It doesn't have peripherals such as memory and I/O integrated onto the same chip. In contrast, a microcontroller like the PIC24FJ128GA010 is a complete system-on-a-chip, containing a CPU, RAM, flash memory, and various I/O capabilities.
Regarding the working registers being located in data memory, this is more a result of architectural decisions by the designers of these microcontrollers rather than a characteristic of microcontrollers in general. PIC microcontrollers use a Harvard architecture, which has separate data and instruction memory, as opposed to the von Neumann architecture used by most microprocessors, which share memory space for instructions and data.
In the case of PIC24F series, the working registers (W0-W15) are part of the data memory space but they are also closely connected to the ALU (Arithmetic Logic Unit) in the CPU for computation. The reason they are part of the data memory space is mainly due to the design of the Harvard architecture, allowing data memory to be directly accessed and manipulated by the CPU for operations.
The general-purpose registers (GPRs) you mentioned, such as EAX, EBX, ECX, etc., in the 8086 are similar to the working registers in the PIC24F in terms of their function. They are used for general data manipulation during processing. However, these registers are not usually considered to be part of the memory space in the 8086 architecture, but are seen as separate entities within the CPU.
Regarding if there are other GPRs in the PIC's CPU, the 16 working registers W0 to W15 are the main ones used for most computations. However, there are other specialized registers like Program Counter (PC), Stack Pointer (SP), and Status Register (SR), but these have dedicated roles.