I've got a SCSI2SD V5.2 board connected to the internal 50-pin SCSI connection of a Mac SE/30. The Mac cannot "see" it, in any configuration I've attempted. I have tried:

  1. Using the stock system 7.0 Apple HD SC Setup, and setting the config variables as (found here):

Set the vendor to the string ” SEAGATE” (yes, there is a single space in front of SEAGATE for a total of 8 characters) Set the product ID to the string ” ST225N” (10 spaces in front for a total of 16 characters) Set the revision to the string “1.0 ” (with a space after, for a total of 4 characters)

  1. Using the "patched" 7.5.3 Apple HD SC Setup on a boot floppy, with the SCSI parameters as above, or as stock.

  2. Imaging a full drive onto the SD card using dd on my Mac, from the image as downloaded from here.

In no configuration does the Mac see the drive. It won't boot from it, it won't mount it when already booted, and no version of HD SC Setup can find it (always says "no suitable drive can be found..." etc). My voltmeter shows the +5V and +12V rails at the SCSI2HD power connector solder points, so it's certainly getting power OK.

This machine is otherwise working and notably, the original internal SCSI hard drive works correctly when it is connected.

Comments below have suggested that further fussing around with it may bear success. But at this point I'm literally not sure what other fussing I am even able to try. Happy for any thoughts. Thanks.

  • 1
    It's a pickle, for sure. Personally, I find it to be much simpler and efficient to build and test the disk image on a modern machine with the help of an emulator, then just copy the image to SD card
    – Brian H
    May 5, 2021 at 21:10
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    While we can't rule out a myriad of possible problems, including a defective SCSI2SD device, I can tell you from my personal experience that these sorts of issues with SCSI devices appearing to not work usually ended up resolved by double-checking the SCSI termination, which is notoriously finicky and under-documented. So I'd probably be trying to get the SCSI2SD to be recognized as a second SCSI device on the bus while booted from the spinning disk.
    – Brian H
    May 9, 2021 at 14:42
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    By coincidence I took delivery of a scsi2sd v5.5 this morning, the external model, which I wish to use with a PowerBook. I also haven't yet had success in getting the machine to recognise it as a drive; the SD card in it was produced using a premade disk image from the internet and reads correctly on an OS X v10.5 Mac (in which HFS is still supported) so that's not the problem. Termination is non-optional, so that's also not the problem. I think it permits live bus logging so I'm going to stick my nose into that next weekend. Will report back if I learn anything.
    – Tommy
    May 10, 2021 at 2:06
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    @BenZotto I don't know yet, exactly, I've got no further than spotting the claim that one should "[u]se scsi2sd-util for SCSI bus event monitoring and general debugging." (cf. the FAQ). I hope to get a chance to stick my nose in shortly.
    – Tommy
    May 11, 2021 at 1:14
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    Observation from poking at it in emulation: the disk images linked seem to include a SCSI Manager 4.3 driver, which definitely doesn’t work on an emulated Mac Plus and some searching suggests possibly requires a Quadra. After using a hex editor to replace it with a pre-4.3 SCSI driver it worked in emulation. I’m going to transport that back to real hardware at some point soon.
    – Tommy
    May 12, 2021 at 4:02

2 Answers 2


By default (without being patched), Apple's stock disk partitioning utility refuses to recognize any SCSI hard drive that isn't on an approved whitelist. This decision to block non-Apple-approved SCSI hard drives from being used without third party disk partitioning software, made 30+ years ago, is at the root of why any classic version of System 6/7/8) refuses to detect a perfectly valid SCSI device.

So...you have three options...the first is to configure your SCSI2SD's vendor and product ID strings to "lie" to Apple's HD SC setup about what it is, therefore allowing you to partition it.

Alternatively, if you have access to it, you can also use third party disk partitioning software, such as Lido7, Silverlining, or Hard Disk Toolkit, to partition your drive. These third-party applications have no artificial limitations on what sort of SCSI hard drives are supported.

Finally, you can use a patched version of Apple's HD SC Setup, which removes the above-mentioned whitelist of supported devices, which is an artificial limitation.


As stated before, you have to format your drive. The apple utility does not support non Apple branded drives. If you have a CD-ROM drive connected to your Apple, you can boot Apple Unix AUX and format the harddisk (emulator) under AUX, which is not so restrective and then use it to install System 7 ....

  • 1
    Also, I don’t know whether it adds anything at this point, but don’t format under OS X; classic Macs expect one partition to contain a driver, and from what I can make out OS X will create the data partition only.
    – Tommy
    May 10, 2021 at 14:31
  • Hi Ralf, thanks for the contribution. I've actually updated the question-- I have tried imaging a full drive (using dd on a modern Mac) as well as using the patched setup tool. Still no dice. Any further suggestions?
    – Ben Zotto
    May 10, 2021 at 21:01

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