Which architectures are Harvard and which are Von Neumann?

Question

I was trying to figure out which of the following architectures can be classified as Harvard (either 'strict Harvard' or modified Harvard, as long as instructions cannot be fetched from data memory, the other way around is fine) and which as Von Neumann and was hoping someone here could help me out / correct me where I'm wrong:

• Motorola 68k: It's unclear to me whether 68k is a (modified) Harvard or Von Neumann architecture.
• PPC: This one's similarly unclear to me
• AVR: All AVR architectures seem to be modified Harvard if I'm not mistaken
• PIC: The PIC microcontrollers (PIC10 to PIC24) seem to be Harvard while PIC32 seem to be Von Neumann (MIP32-based)
• SuperH: Only SH-2A and SH-4 seem to be Harvard
• 8051: Seems to be Harvard as well

Answer 1

Abbreviations

VNA = Von Neumann Architecture
HVA = Harvard Architecture
MHVA = Modified HVA

• Motorola 68k is VNA, it has a single memory for program and data.
• PowerPC is VNA, it has a single memory for program and data.
• AVR is MHVA because it has separate program and data memory and the LPM instruction can be used to load data from program memory.
• PIC16 is HVA because it has separate program and data memory and no instruction to read from program memory.
• SuperH are usually VNA but some DSP models are HVA.
• 8051 is MHVA because it has separate program and data memory and the MOVC instruction can be used to load data from program memory.