SD module

BurgerDisk - a daisy-chainable Smartport hard drive

Warning - everything in git, and not a release, is not necessarily fully tested.

This device provides the Smartport-capable Apple II with an SD-card-based hard-drive, like the SmartportSD, SPIISD or FloppyEmu projects do.

Contrary to those, the BurgerDisk firmware handles a daisy-chain port and allows you to have more Smartport devices and/or dumb floppy drives connected behind it.

Contrary to the SPIISD v2 and FloppyEmu projects, BurgerDisk is free software and free hardware, and licensed in a way to keep it that way.

Contrary to the SPIISD v2 and FloppyEmu projects, BurgerDisk has no screen UI, and contrary to the SPIISD v1 project, it has no "boot partition" selection button. The Apple II will be able to boot from the first partition when booting from slot 5. This is both a choice - I wanted this device to resemble a period-correct hard drive - and a limitation - there are no extra digital GPIOs available on the Nano board.

The code of this firmware is based on:

• Apple //c Smartport Compact Flash adapter, written by Robert Justice <rjustice(at)internode.on.net>
• Ported to Arduino UNO with SD Card adapter, written by Andrea Ottaviani <andrea.ottaviani.69(at)gmail.com>
• FAT filesystem support, written by Katherine Stark
• Daisy chaining is based on SmartportVHD's reverse engineering, written by Cedric Peltier

Building the BurgerDisk

Full instructions for building your own BurgerDisk are available in the BurgerDisk build instruction page.

Using the BurgerDisk

Plugging in

Plug the BurgerDisk to your Apple II, or to the previous Smartport device in the chain. Plug the next device to the daisy port of the BurgerDisk.

When daisy-chaining, the usual Apple II rules apply:

• first the dumb 3.5" floppy disk drives (like the Apple 3.5 drive)
• followed by Smartport devices (like BurgerDisk, Unidisk 3.5", Fujinet, SPIISD, etc)
• followed by dumb disk drives (like the Disk //c)

So far, BurgerDisk has been tested in the following configurations:

• Alone on the //c and IIgs external floppy connector
• computer => BurgerDisk => Disk //c
• computer => Unidisk 3.5 => BurgerDisk
• computer => Unidisk 3.5 => BurgerDisk => Disk //c
• computer => BurgerDisk => Unidisk 3.5 => Disk //c

It has been tested with the following computers:

• Apple //c A2S4000, ROM3
• Apple //c A2S4100, ROM4x
• Apple IIgs, ROM 01

More tests results are available.

Configuring disk images

The firmware will open and present between one and four partitions. If a config.txt file exists on the SD card, it will use the first four lines as filenames for the partitions to open. An optional fifth line containing "debug=1" will turn debug messages on.

For example, this will present prodos.po and total_replay.po, and turn debug on:

prodos.po
total_replay.po


debug=1

If no config.txt file exists, the firmware will search for PARTx.po files, with x between 1 and 4.

Compatibility notes

The firmware is compatible with SPIISD v1 and SPIISD v2 boards. It fixes two bugs in their firmwares:

• Too slow init preventing the partitions to be visible by ProDOS after booting from internal floppy,
• A non-recoverable freeze on A2S4100 Apple //c with the memory expansion board.

But,

• Of course, running this firmware on an SPIISD board will not allow for daisy chaining.
• For daisy-chaining, the BurgerDisk firmware makes use of pins that the SPIISD boards use for button(s) and/or LCD. If you want to replace the SPIISD firmware with BurgerDisk's, it is safer to unsolder the buttons and remove the LCD. The BurgerDisk firmware does not handle any buttons or LCD anyway.

Licensing

This firmware is licensed under the GPL v3.

The PCBs and enclosure are licensed under CC BY-SA 4.0.

This means that anyone is welcome to use, modify, distribute and sell hardware based on BurgerDisk. Using and modifying does not require you to do anything. Distributing and/or selling requires you to provide the source files for the firmware and the PCBs, under the same licenses. It can just be a link to this repository if no modification is made. If modifications are made, think free software, and consider submitting pull requests, it could help avoiding fragmentation.

Thanks and acknowledgments

Many thanks to Robert Justice, Katherine Stark and Andrea Ottaviani for the initial work on a simple SD-based Smartport device.

Many thanks to Cedric Peltier for his work on SmartportVHD, which does support daisy-chaining, but is sadly abandoned, and based on a weird-ass development board. It was very well documented and helped me a lot implementing daisy-chaining.

Many thanks to Ralph Irving, who spent many hours beta-testing and pinpointing bugs I could not have fixed without his help (for lack of hardware).

Thanks also to Steve Chamberlin of BMOW, for documenting a lot of their Smartport/FloppyEmu work on their blog.