I recently purchased an SD2IEC from from The Future was 8-bit.  While the device is awesome, I felt the documentation was less than stellar. And that led me to put together this resource to help others who are first experimenting running SD Cards on the Commodore series of computers. I consider it the unofficial SD2IEC manual and I hope it helps others on their awesome 8-Bit retro-computing journey!

For those of you who might not be familiar with the SD2IEC, a little background. The venerable 198o’s Commodore line of computers, which includes the C64, C64C, C128, C16, Plus/4, VIC-20 and the portable SX-64 used a propriety disk connection known as IEC (also known as IEEE-488). This is not the parallel version used on the Commodore PETs, but rather a stripped down serial version that was designed specifically for the consumer lines.  The Commodore VIC-20 was the first computer to support this new serial IEC in both hardware and software form.

The IEC serial bus is used for many different types of peripherals, the most common two being printers and disk drives. The tape drive was also on this serial bus, albeit on a different physical connector.  The SD2IEC is a device which emulates the IEC protocol and translates the data being read from and written to an SD card. This allows Commodore computers to read and write to SD cards rather than than 5.25″ floppy disks.  A 2GB SD card for example can store hundreds of Commodore “D64” disk images and takes up almost no room compared to the Commodore 1541 disk drive and a stack of floppy disks.  Additionally an SD card is far more reliable and less prone to damage as compared to floppies.  If you add the Fastload Reloaded cartridge to the mix the SD2IEC performance will be five to six times faster than using floppies.  Let’s move on to getting started in this unofficial SD2IEC manual!

SD2IEC Compared to a 1541 Disk Drive

Getting Started with the SD2IEC (Unofficial SD2IEC Manual)

When you receive your SD2IEC you’ll notice it only comes with a single sheet of paper with some very basic instructions, rather than a full SD2IEC manual as you might expect of a product such as this. At least a nice PDF you can download right? Well you’ll get no such luck with this product. And that’s really unfortunate for less technical users who just want to play the games they played as kids on their C64.  Just a few steps and you’ll be up and running!

Prepare the SD Card

One word of caution as I found out quickly, you need to use a smaller card. I tried several 32, 64, and 128 GB cards that were laying in my drawer and none of them were compatible. The SD2IEC would not read them.  I wound up purchasing a Transcend five pack of these 2GB cards from Amazon on they worked perfect first try. So if you’re having problems that’s the first place to look, especially if everything else seems like it is right.  A sure sign is that you’ll be unable to even list the main directory of the card once you boot the C64.

Formatting the SD Card for the SD2IEC

The first thing you’ll want to do is get and format an SD card. If you do this on a Mac, download the Official SD Card Formatter, rather than the Apple Disk Utility as it only supports Apple File System or exFAT.  Neither are compatible with the SD2IEC.  You need to format the card with FAT16 or FAT32 (FAT32 being the preferred format). If you’re using Windows just select FAT32 from the File System drop down and you’re good to go. Another recommendation is not to use an SD card which has been previously used for some other operating system such as a Raspberry Pi. It can be very difficult to get those cards reformatted properly for the SD2IEC.  Again, I just recommend buying a new card.

Preparing the Newly Formatted  SD2IEC SD Card.

Once the card is formatted its now ready to be prepared for use. Head on over and download the CBM File Browser.

The CBM File Browser is a set of Commodore programs designed for specific machines that will allow the Commodore computer to browse the disk images called “D64 files” that you place on the SD2IEC’s SD card. Although these programs are not strictly needed, they do make the task much simpler.

Select the CBM Browser for your specific Commodore computer and copy it into the root folder of the SD card. If you’re using a Commodore 64, copy the FB64 file. If you’re using a Commodore VIC-20, copy over the FB20 file, and so on. On some versions of Windows it has been reported that the Explorer will add an extension to the file.  If this happens you will need to rename the file and remove everything including the period.  In other words the file on the SD card should just be named FB64, rather than FB64.EXE or FB64.TXT.

Copy D64 Files over to the SD Card

The next step in our unofficial SD2IEC manual is to copy over your D64 Commodore Disk Images to the SD card.  It is recommended that you create directories and drop the files into them.  This is especially true if you have a multi-disk game. Games like the Ultima series of role-playing games come on several disks and will be much easier to play if they are in their own directory. You can swap disk images with the buttons on top or an AUTOSWAP.LST file, but more on that later.  Strictly speaking though, directories are optional and you can place all D64 images right in the root of the SD card along with the FB64 program.

With the SD2IEC card still in your Mac or PC, copy over any D64 disk images that you want on the card.  You can find many ready to download D64 images just by doing a quick Google search. We don’t condone piracy, so don’t download files that have not been released in the public domain or that you don’t already own a copy of.

Connecting the SD2IEC for the First Time

As we move forward in our unofficial SD2IEC Manual, we’re ready to put our SD card and SD2IEC to use! Make sure your Commodore 64 (or whichever Commodore you’re using) is setup on your desk and will load to the basic screen.  Once your there turn off the computer and unplug the power connector from it.

Connecting the SD2IEC

There are two types of SD2IEC’s.  One is powered from the user port, while the other is powered from the tape port. I personally chose the tape port version since it leaves the user port available for peripherals and I can’t imagine I will ever use the tape port.  Regardless, the connector is labeled with a top and bottom side.  Make sure top is up and plug it into the corresponding port on your Commodore computer. Plug the 6-pin IEC connector into the IEC port on the back of the Commodore.

Install the Fastload Reloaded Cartridge (Optional)

If you also bought a Fastload Reloaded cartridge, now is the time to install it. It simply plugs into the cartridge port of the Commodore 64. While this is completely optional it will dramatically increase the speed of loaded software from the SD2IEC (or even a real 1541 disk drive). It is important to note that the SD2IEC will not work with original Epyx Fastload from the 1980s.

Turn on the Computer

All that’s left before we get started is to plug the power back into your Commodore and turn on the power switch.

Note: I highly recommend if this is your first time using the SD2IEC that you have any other peripherals disconnected. Do not install modems, daisy chain disk drives, printers, or other devices with the SD2IEC installed until you know everything is working correctly.

If all goes well, the C64 will show the welcome to BASIC message and the ready prompt (including the FASTLOAD logo if you have the Fastload Reloaded installed).

Connecting the SD2IEC for the First Time

Now in our unofficial SD2IEC Manual lets learn some basics of reading and writing disks on the SD card.

Listing the root directory of the SD2IEC without a Fastload Reloaded

If you’re not using a Fastload Reloaded you’ll need to type the following Commodore BASIC commands to list the directory of the SD2IEC.

LOAD "$", 8

Listing the root directory of the SD2IEC with a Fastload Reloaded

If you’re using the Fastload Reloaded, the command is much simpler.  Simply type a $ (dollar sign) and press return.

Using the CBM File Browser – Select the Disk Image to Mount

To use the CBM File Browser to mount an image and load a game is fairly simple.  Simply type the following commands:

LOAD "FB64",8,1

Use the cursor keys to browse the menu to select the disk image you want to mount and then simply select the program in that disk image that you wish to load and press return.

Using the CBM File Browser – Select the File to Load From Disk

The next screen will show you the contents of the disk image you just selected to mount.  Select the file you want to open and press return.

Using the CBM File Browser – Play your Game!

Once you press return, the CBM File Browser will mount the disk and launch the file you selected.  In a matter of just a few seconds you should see your game on the screen and ready to play! In my case I am playing Spelunker, one of my all time favorite C64 games (even if it was ridiculously hard to win).

Some Advanced SD2IEC Features

There are some additional SD2IEC features that the average user may not be interested in, but could help if your a more advanced user.

Playing games with Multiple Disks (or disk images)

Inevitably you’re going to run into a game or application that contains multiple disks.  This can be troublesome since once you exit the CBM Disk Browser you no longer can see the contents of the SD card.  Nope. Commodore’s still can’t multitask or open separate windows, even today!

The good news is that the creators of the SD2IEC thought of this very problem.  You’ll need to create a file called AUTOSWAP.LST in the same directory with your game’s D64 disk images. You can create this file in any text editor such as Notepad on Windows or TextEdit on the Mac.  This file should simple contain a list of D64 images in the correct order. Example:


Once you’ve done this, open the FB64 program again and open the directory that contains your disk image.  Now instead of selecting a disk image, press Q to exit the program. Press the DiskSwap button on the SD2IEC (the DiskSwap button is the one closest to the IEC cable).  This will select the first disk. Enter the C64 load commands (or follow whatever instructions your game came with) as shown here:

LOAD "*",8,1

This will load the game.  When the game asks you to insert disk 2, press the DiskSwap button the SD2IEC and it will mount the next disk in the AUTOSWAP.LST file. When you reach the last disk, the SD2IEC will simply start the list over and select the first disk again.

Changing the SD2IEC Device Address

By default the SD2IEC will be Disk ID 8. This is the default Commodore 64 Disk ID.  If you want to daisy chain the SD2IEC behind an existing Disk 8 you will want to program the SD2IEC to act as Drive ID 9.  Enter this command to that:


If you want to save this to the SD2IEC’s memory so that it stays Drive ID 9, enter the additional command:


This can of course be changed back at any time by swapping 8 & 9 in the above commands.

And that’s it!  Now you’re an SD2IEC guru!