Apple II expansion card using a Raspberry Pi for I/O w/o Raspberry Pi

more details on the website please check out carefully for details on the pictures

Described by the owner of the project below :

Purpose

The purpose of this project is to provide I/O for an Apple II series 8 bit computer via a Raspberry Pi Zero 2 W which is powered by the Apple II expansion bus. This includes using the attached RPi Zero 2 W for it's storage, network and processor to provide new functionality for the Apple II.

Features

Boot message which waits for RPi to be ready

ProDOS bootable drive from image stored on RPi

Linux bash shell to the RPi from the Apple II including some VT100 support via -SHELL from ProDOS

Load binary files directly from the RPi to the II (via dynamic virtual drive of current working directory on the RPi)

Update Apple II firmware in place from image on RPi (note, this is done per slot)

Supports two drive images at the same time

Supports "RPI" command from BASIC to execute Linux commands from the command prompt or inside BASIC programs: 10 PRINT CHR$(4);"RPI ls -al /"

Project Status

Classic Hardware

So far, this is still a project and not a finished product. The current prototype is on the seventh revision. I have sold about 60 boards including previous prototypes. There are several hundred in the wild between self made and ones purchased in places like that were made by others. The seventh prototype is functionally equivalent to the sixth other than support for write-protect and reintroducing EPROM support. The fifth revision was similar and compatible with the sixth, other than a new jumper to select internal/external power on the sixth.

The card enables the Apple II to boot from and write to virtual hard drive images stored on the RPi in any slot (except slot 3), execute Linux commands from Applesoft BASIC and run a bash shell with VT100 emulation. The code has very few tests and is incomplete. Note that currently the firmware assumes an 80 column card is in slot 3 and than you have lowercase support. Most development has been done with an enhanced Apple //e with the card in slot 7. If you have other drive controllers earlier in the boot cycle, you can still boot from the Apple2-IO-RPi. For example, if the card was in slot 4, you could type PR#4 from the BASIC prompt to boot the card. Note that the Raspberry Pi Zero W (and W 2) consume 170 - 250 mA and there is only 500 mA available to all expansion slots according to Apple. It is not recommended to have a lot of other cards in the system at the same time. With the sixth revision of the prototype, it is possible to remove the power jumper and run the RPi on an external USB power source. If configured for external power, note that the card's firmware will hang on boot without USB power on as the latch chips are powered by the 3.3V output of the RPi.

If you have a problem or idea for enhancement, log an issue here or start a discussion. I recommend starring/watching the project for updates on GitHub. You are welcome to fork the project and submit pull requests which I will review. The latest version has an in-memory virtual drive representing current working directory in Linux for ease of copying files between Linux and ProDOS when the drive 1 is not specified as a file.