Pocket Serial Host acts as an Apple II disk drive

apple-II-pocket-serial-host

[Osgeld] is showing off what he calls a sanity check. It’s the first non-breadboard version of his Pocket Serial Host. He’s been working on the project as a way to simplify getting programs onto the Apple II he has on his “retro bench”. When plugged in, the computer sees it as a disk drive.

The storage is provided by an SD card which is hidden on the underside of that protoboard. This makes it dead simple to hack away at your programs using a modern computer, then transfer them over to the retro hardware. The components used (starting at the far side of the board) are a DB9 serial connector next to a level converter to make it talk to the ATmega328 chip being pointed at with a tool. The chip below that is a level converter to get the microcontroller talking to the RTC chip seen to the right. The battery keeps that clock running when there’s no power from the 5V and 3.3V regulators mounted in the upper right.

The video after the break shows off this prototype, the breadboard circuit, and a demonstration with the Apple II.

[Thanks Brendan]

19 thoughts on “Pocket Serial Host acts as an Apple II disk drive

  1. I agree with William good job but
    The first Apple II computers 1 MHz, 4 KB of RAM
    atmega328 20 MHz 32 Kbytes flash
    Just had to make the comparison your adapter is more a more powerful computer than what is it connecting to.

  2. Well, hello HAD, been a while.
    I just wanted to make note that the software running on the Apple II was written by David Schmidt, based on previous work done by Terence J. Boldt … I just did a port for AVR

  3. Wow, that is a nice piece of kit!
    The a2 was my first computer and will always have that special place. a2 posts are too far and in between, thank you for this.

    I’ve been using a CFFA3000 for this purpose, but it’s a closed product and not too hackable.
    I’ve never been able to wrap my head around the low level disk controller protocols to design such a thing myself.
    It was amazing what Woz could do in software for sure, but talk about complicated ;}

    1. The board works with a specific ProDOS driver and acts as a hard drive; it doesn’t actually emulate any physical hardware or heads seeking back and forth or the like, but instead is a block device. You can’t boot off of it, for instance.

  4. DE9. The B size D-subminiature (sub-miniature compared to the honking big connectors before them) is what’s used for 25 pin parallel and serial connectors and weird things like DB13W3 SUN monitor connections.

    1. to time/datestamp the files on the disk volume within the image, it was a requested feature as a rtc is not standard hardware on an apple II

  5. Would somthing like this work with a IIGS one poped up under a sink in my high school and my friend and i have been meaning to get an operating system running on it rather than just using apple BASIC (or whatever the command line on it is called) but we dont have any disks for it just a 4.5 inch drive and a borked 3.5 inch drive

    1. yes, the disk image that comes with ADT fits on a 140k 5.25 inch floppy, though I dont know how compatible it is with running GSOS off the SD card, I dont have one to try.

      I know the 8 bit desktop runs, but its more or less a shell launcher, and on the other side of that geos will crash as of right now cause it overwrites the driver in ram

  6. I was thinking of doing something similar with my 5 apples. My question is … are for sale? and yes, what is the price and where I can buy.
    Congratulations.

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