I was under the impression that the Raspberry Pi's ARM processor, although having an armhf microarchitecture, still followed the Von Neumann architecture (principally sharing main memory for instructions and data).

However I came across this single line in a Computer Science textbook (A Level Computer Science for AQA Unit 2, Kevin R Bond 2016, pg265)

The Raspberry Pi computer is based on the Harvard architecture

Having searched online, I can't find any solid sources that either prove or disprove this statement. Is this in error? I would appreciate a source given in an answer.

(I'm aware the Raspberry Pi SE exists, but given the fact that the tag does not exist there, I thought it more appropriate to post it here)

Even though the internal architecture of the CPU might be harvard-like, with separate instruction and data caches and buses, the rest of the SoC still only has got one main memory, and both instruction and data buses connect to the same memory. From https://en.wikipedia.org/wiki/ARM9:

With this design generation, ARM moved from a von Neumann architecture (Princeton architecture) to a Harvard architecture with separate instruction and data buses (and caches), significantly increasing its potential speed. Most silicon chips integrating these cores will package them as modified Harvard architecture chips, combining the two address buses on the other side of separated CPU caches and tightly coupled memories.

From the linked page about modified Harvard architecture:

Most modern computers instead implement a modified Harvard architecture.

The most common modification builds a memory hierarchy with a CPU cache separating instructions and data. This unifies all except small portions of the data and instruction address spaces, providing the von Neumann model. Most programmers never need to be aware of the fact that the processor core implements a (modified) Harvard architecture, although they benefit from its speed advantages. Only programmers who write instructions into data memory need to be aware of issues such as cache coherency.

The same also goes for any modern x86 chip.

This doesn't pose any issue for Raspbian, which is just a special recompile of normal Debian for Raspberry Pis; the main difference in raspbian is that it has got a different arm target (armv6+vfp hardfloat) than the other existing arm debian distributions (which target either armv4t or armv7+vfp hardfloat).

It's not specifically the pi that uses the architecture, but the processor it has.

The original raspberry pi uses an ARM 11 chip (Later versions migrated to the CORTEX-A chips), and ARM transfered from Von Neumann architecture to Harvard with the ARM9 chip

https://en.wikipedia.org/wiki/ARM9

Additionally, this is from ARM's product page

https://www.arm.com/products/processors/classic/arm9/index.php

Note, It is assumed that as nothing has been mentioned about there being any changes to the architecture, the CORTEX-A cores also maintain this too