Setting up your vintage (classic) 68k Macintosh – Using a SCSI2SD adapter

SCSI2SD adapter card
SCSI2SD adapter card

I recently purchased a SCSI2SD V.5 adaptor (3.5″ and 2.5″) to replace a failing 1980s SCSI HD, and realized once I had it set up I could “image” the Micro-SD card to make boot-able images anyone could use.

So, similar to my entry on setting up using a floppy disk, and setting up using an Iomega Zip Drive, I created boot images for System 6.0.8 and System 7.5.5 for setting up an SD card for use with SCSI2SD.


  1. Your classic 68k Macintosh turns on, and is prompting you to insert a disk.  If your 68k Macintosh does not turn on, or does not show the insert disk icon, you may need to do some repair work before you proceed.
  2. Your classic 68k Macintosh supports an internal SCSI hard drive, and/or an external SCSI hard drive, although you will need to have an enclosure or an external adapter for your SCSI2SD adaptor so to use it externally.  Note, for Powerbook systems that only support 2.5″ SCSI drives, a Powerbook Edition of the SD2SCSI adaptor can be used to replace the internal drive.
  3. You have a SCSI2SD adaptor, you MAY be able to use these images with a Compact Flash card of the correct size and a CF2SCSI adapter, if you can, let me know.
  4. You have a 4GB, 8GB, 16GB or 32GB SD or MicroSD card you plan to use with your SCSI2SD adaptor.

1. Determine if you can use this method

This method will work for the majority of 68k Macintosh computers except: The 128K, 512K, 512Ke.  These three 68k systems do not support internal or external SCSI.  You will need to use one of the other setup methods I’ve previously identified, with the best option being buying and using Floppy-Emu to boot from 400KB SS SD floppy disk images.

For setting up your SD2SCSI card, I suggest either:

  1. using one of the images I’ve provided as long as it’s size is equal to or less than the capacity of your card (see note for size in bytes under the table below).
  2. using one of the smaller images I’ve provided as your SCSI 0 drive, and leaving the rest of your card for use as your secondary + drives (see section 3.2 below).  For example if you have a 2GB card, you might want to use my 1GB image, and setup the rest of your card as a secondary drive (SCSI 1 etc),
  3. creating your own image file and initializing it using SoftMac, or
  4. use some other method of setting up your SD card, e.g. boot from a floppy, CD, etc.

2. Selecting your bootable drive image

I’ve created images containing the minimum versions of System 6.0.8 and System 7.5.5, and several utilities and drivers (see my entry on creating a bootable disk starting with a disk image).   I haven’t created any image files larger than 2GB, I’m assuming if you have a card larger than 2GB you plan to setup your SD card as multiple virtual drives (see Section 3.2 below).

System 6.0.8System 7.5.5Apple IIe1size in bytes2Sector count3Block Count4
  1. The Apple IIe images have been pre-configured to support the Apple IIe Card.   They have System 7.5.5 as the “blessed” System, and they have been partitioned to include two 32MB ProDOS partitions with the remaining space containing an HFS formatted partition.   See my entry on using an Apple IIe Card for more information (coming soon)
  2. Because manufacturing issues, the number of GB your SD card says it can handle might not be the actual amount.   It could be a bit more, or a bit less.  I have two 4GB cards, one that has a capacity of 4,024,434,688 bytes, and another that has a capacity of 3,965,186,048 bytes. These images were purposely created to be smaller than the maximum stated capacity of the SD card to compensate for bad sectors and variations in storage capacity.
  3. Used in section 3 when configuring the size of your SCSI drive(s).  The default sector size in SCSI SD is 512 bytes, the sector count is the size of the image file in bytes divided by the sector size.   If the sector size is NOT 512 bytes you’ll need to calculate this value for yourself.
  4. Used with DD: bs=1M count=## for extracting the first portion of your SD card to an image file to edit/update.

3. Configuring your SCSI2SD adaptor

You will need to configure your SCSI2SD adaptor based on the size of SD or microSD card you plan to use.  Since I do NOT have a SCSI2CF adapter I can’t provide any guidance for you, or know if you even have to do anything.

  1. Format the SD card you plan to use, if you are using windows I suggest doing a full format vs. a quick format to make sure the card is wiped clean and has no errors.
  2. Download the correct setup software from CodeSRC, make sure you get the correct software based on your version of the adapter v3/v4/v5 vs. v6.   The software is available for Windows 32, Windows 64, Linux and Macintosh OS X.
  3. Run the setup software
  4. Insert the SD or microSD card in to your SCSI2SD adaptor
  5. Connect the USB cable from your computer to your SCSI2SD adaptor

3.1. If you want to setup your SD card as a single drive

Not recommended, but it’s up to you.  Setting up your SD card as multiple hard drives will make your life simpler.  Under the Mac OS, there are several limitations for what you can do to the drive the System files are installed on.   By having at least 2 virtual drives you can save your self a lot of grief.

Double check that the byte size of your SD card is equal to or greater than than the byte size of the image file you plan to use.

  1. Select device 1
  2. Set the sector size to 512
  3. Set the sector count size based on the size of the image file, e.g. my 2GB image file is 1,971,322,880, so the sector count is 1,971,322,880 / 512 = 3850240
  4. The device size should auto adjust, e.g. for the 2GB image file the size is 1.84 actual GB (a MB, GB etc. should be a multiple of 1024, but for marketing reasons storage uses a multiple of 1000)
  5. You should be able to leave the rest of the settings as the default unless you have a reason to change the values (see Figure 1)
  6. Select save to device
    • If you get the message “Save Failed” you’ve set the total sector size of your Device to be larger than what your card can hold.
  7. Once saving is complete disconnect the USB cable from the SCSI2SD adapter
  8. Eject the SD card from the SCSI2SD adapter go to section 4.
Figure 1: Device 1 configuration

3.2. If you want to setup your SD card as multiple drives:

Double check that the byte size of your SD card is greater than than the byte size of the image file you plan to use.

For this example I’m going to use a 16GB SD card (15,794,700,288 bytes) (see Figure 2), and my 2GB image file (1,971,322,880 bytes) for my SCSI device 0.

  1. Follow the steps from section 3.1 above to setup device 1 based on the size of the image file you selected as your SCSI device 0.
  2. Select Device 2 (Figure 3)
  3. Select Enable SCSI Target
  4. For SD card start sector, select Auto
  5. For this example, because I used 1,971,322,880 bytes for device 1, I now have 13,823,377,408 bytes left to work with, which is equal 26,998,784 sectors.
  6. Putting 26998784 sectors in to the sector count give me a Device 2 with a size of 12.874 GB (Figure 3).
  7. If I wanted Device 2 to be smaller I’d reduce the sector size, and use the remaining sectors in Device 3 (and optionally 4)
  8. I suggest that you leave about 50 to 100MB empty (100,000 to 200,000 sectors) un-allocated at the end of your SD card to prevent future issues if you want to backup and restore the contents of your SD card to a different SD card.  As I mentioned earlier the available space on these cards isn’t standard, and can vary by 50 to 100MB.
  9. Once you’ve finished setting up the Device tabs, press the Save to device button.
    • If you get the message “Save Failed” you’ve set the total sector size of your Device(s) to be larger than what your card can hold.
  10. Once saving is complete disconnect the USB cable from the SCSI2SD adapter
  11. Eject the SD card from the SCSI2SD adapter go to section 4.
Figure 2: Capacity of 16GB card
Figure 3: Device 2 configuration

4. Copying the image file to your SD, microSD or CF Card

I’ve moved this section to a separate blog entry for how I write the images I create to the SD and CF Cards and how to create your own images if you don’t want to use one of mine.

Once your done, re-insert the SD card in to your SCSI2SD adaptor, connect the adapter to your classic Mac’s SCSI bus, and you’re ready to go.

If you used option 3.2 above and created more than one “drive” on your SD card, you’ll need to initialize and partition the additional drive(s).

If you plan to use any System older than System 7.5.2 do not create partitions larger than 2GB, there also seems to be a limit to the number of partitions you can have, I was only able to make 12, this isn’t a limit per drive, this is the total limit across all drives.

5. Another Option for setting up your SCSI2SD

Remember you could always start with one of my images set as SCSI 0, but once you have your SCSI 1 drive setup how you want, go back in to the SCSI2SD config software, and switch the SCSI IDs, so that my image becomes SCSI 1 (or later) and your newly created, partitioned drive becomes SCSI 0 (your boot drive).   This will let you create a SCSI 0 boot drive partitioned exactly how you want.

15 thoughts on “Setting up your vintage (classic) 68k Macintosh – Using a SCSI2SD adapter

  1. Thank you very much! I can confirm that the instructions worked on macOS High Sierra and I was able to boot my Macintosh SE without a floppy. I should mention that dd took quite a while for me, around 3 hours.

  2. I’m getting an error from Chrome when I attempt to download these images: is dangerous, so Chrome has blocked it.

  3. Hi. This looks great, and I’m really looking forward to trying it out. Just our if curiosity, once this is set up, is there a way to write additional software to the SD card? There is lots of software one can download, but I’ve no way to write it to a floppy, so I’d love to be able to just write it directly to the SD card. Thanks!

  4. I have the 5.1 board, and am running into issues getting the Mac (SE HDFD) to recognize the SCSI device. Is there any tips/tricks needed to get this going beyond setting the size & ID for the devices? Which firmware version(s) have you been successful with?

  5. Another thing to do with the card: update the vendor/product/revision info so it masquerades as an Apple-original device (eg, the SEAGATE ST225N rev 1.0). The fields are case-and-position sensitive, so you can’t just drop in the names any old way (below, replace asterisk with a space):
    vendor: *SEAGATE
    product ID: **********ST225N
    revision: 1.0*

    With this config, the native Apple SC HD application will recognize the drives; you don’t have to use patched versions, etc., on those old machines that would otherwise ignore them.

    • Thanks for point this out, I’ve used the patched version of Apple SC HD for so long I didn’t even bother trying to spoof a compliant drive.
      Did you get this working with your Mac SE HDFD?

  6. Hi Steve – would this work with a color classic with an LC575 board? Would I be able to do an external install or would I be better off with an internal install for this configuration?


    • Hi CT, not sure, have you modded you CC to 640×480? If so it should see your CC as an LC575 and work. For internal vs. external that’s up to you, when I had it installed in my un-modded CC I was using it internally.

  7. Hey! Thanks for these guides, it was a great and complete set.
    I like your 2GB image and would like to use it as a ‘starting point’. It seems quite complete. Two questions:

    1) Is the RAM affected by the networking stuff on it or can that be further slimmed down?
    2) Assuming I want to have several drives, the first one being your image and the others being simply empty 2GB drives for storage. I have SCSI2SD v6 and a Mac Classic II. How can I achieve this?

    Thanks for your efforts!

    • Hi Daniel,
      1. the networking stuff isn’t enabled by default so there shouldn’t be an impact on your RAM. It’s on the image but would need to be installed.
      2. You can write one of my images to the first part of your SD card, then set up the remaining parts of the card as additional drives following the instructions in section 3.2 of this post.

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