Initializing and Partitioning your real and emulated drives for a your 68k Macintosh

Last updated on December 31, 2020

One of the most popular entries on my site is my guide to setting up a SCSI2SD adapter with one of my ready made System 6.0.8 or System 7.5.5 images for use with 68k Macintosh systems. This entry describes the different ways to initialize your drive, or drive image.

Overview

This entry contains:

1. A description of what a drive image is vs. a volume/partition image, and a description for how to use DD to covert between
2. A list of tools that can be used to create, initialize and edit drive and volume/partition image files
3. A description of how to initialize a drive image or real hard drive/removable drive using a patched version of HD SC setup 7.3.5

1. Drives, Drive images, Volumes and Volume (partitions) images

Through out my site I refer to my bootable image files as Drive or Volume images, depending on the tools you want to use to edit them with, or the devices you want to copy them on to, you’ll typically need to know which to use:

• A Hard Drive or Removable Drive Image : contains a binary copy of the complete contents of an initialized drive including the drive’s boot driver and partition information.   Example, Figure 1 is the contents of a Drive Image viewed in my patched version of HD SC Setup 7.3.5 in SoftMac. This type of image is required for SCSI2SD, Hard Drives, Removable Drives such as Zip Drives, and Jaz Disks, and bootable CD-ROMs.
• A Volume or Partition Image: contains a binary copy of a single Macintosh volume or partition from a hard drive or removable drive.  When most emulators refer to a hard drive file, a Partition/Volume Image is typically what they are actually referring to and support.  These images lack both the boot sector, partition map. Used by FloppyEMU.

1.1 Converting a Drive image file in to one or more Volume/Partition images

You can use programs like DD to extract volume/partitions from a drive image to one or more separate files. To do so can be tricky and requires that you know exactly where each partition/volume starts and ends in the drive image. For my drive images you can use the following commands (a more detailed example can be found in my blog entry on how I setup my SCSI2SD drive for my LC475):

Image Size	DD commands (Windows Examples)
100 MB (Zip drive)	dd if=d:\OS_755_100MB.dsk of=d:\volume.img bs=49152 skip=1 –progress Total image size: 94,371,840 bytes, need to skip the first 48KB
1GB (Jaz drive, SCSISD)	dd if=d:\OS_755_1GB.dsk of=d:\volume.img bs=16384 skip=3 –progress Total image size: 985,661,440 bytes, need to skip the first 48KB, and the block size must be a number that can divide both, so 16k.
2GB (Jaz drive, SCSISD)	dd if=d:\OS_755_2GB.dsk of=d:\volume.img bs=16384 skip=3 –progress Total image size: 1,971,322,880 need to skip the first 48k, and the block size must be a number that can divide both, so 16k.

1.2 Converting a Volume/Partition image back in to a drive image

The following examples show how you can merge the extracted volume/partition back in to the drive image:

Image Size	DD commands (Windows Examples)
100 MB (Zip drive)	dd of=d:\OS_755_100MB.dsk if=d:\volume.img bs=49152 seek=1 conv=notrunc –progress Need to skip the first 48KB (seek 1, bs=48k)
1GB (Jaz drive, SCSISD)	dd of=d:\OS_755_1GB.dsk if=d:\volume.img bs=49152 seek=1 conv=notrunc –progress Need to skip the first 48KB (seek 1, bs=48k)
2GB (Jaz drive, SCSISD)	dd of=d:\OS_755_2GB.dsk if=d:\volume.img bs=49152 seek=1 conv=notrunc –progress Need to skip the first 48KB (seek 1, bs=48k)

2. Editing my Macintosh 68k bootable image files

The table below lists the different tools I’ve assessed and indicates if they can be used to edit drive and/or partition files. Personally I mainly use Basilisk II to edit my image files, and use DD to split larger drive images in to a set of partition images then merge them back together after I edit them.

1. P: can read/write Partition files (also called Volume files)
2. D: can read/write Drive files, D(1) indicates the software can only work with a drive file with a single partition
3. I: can initialize new Drive files, these are files
4. R: can read but not be used to add new files to an image
5. E: can read and be used to add new files to the image (edit)

Emulator/Tools	Features	Windows	Linux	Mac OS
My image files		Yes	Yes	Yes
Basilisk II	P, D(1), E	Yes	Yes	Yes
Cockatrice III	?	?	?	?
HFSExplorer	P, D, R	Yes	Yes	Yes
HFVExplorer	P, E	Yes	No	No
MAME	D, I, R	Yes	Yes	Yes
Mini vMac	P, E	Yes	Yes	Yes
SoftMac	P, D, I, E	Yes	No	No
PCE / macplus	P, R	Yes	Yes	? (untested)

3. Initializing / partitioning a Drive or Drive image

To use a real hard drive, removable media or drive image you first have to initialize it to add the drive’s boot driver and partition information

3.1 Limitations when initializing/partitioning a drive under System 6.x and System 7.x.

1. You can’t change the partitions on the drive you are currently booting from (which is why setting up your card as more than one “drive” when using SCSI2SD will make your life easier)
2. HD SC Setup provided by Apple only works with apple drives, luckily a patched version of HD SC Setup was created that works with any drive.
3. HFS has a limit of 65,535 files per logical disk (e.g. partition). A way around this is to use a tool like ShrinkWrap to create mountable disk images.
4. System 4.1 to 6.08 can only support 2 GB partitions, System 7.5 introduced support for 4 GB partitions, and System 7.5.2 introduced support for 2 TB partitions for some systems (See Apple KBase Article 8647)

3.2 Deciding what types and sizes of partitions you plan to create

If you plan to use the Apple IIe card you will want to create at least one (max two) 32MB (yes MB) partitions that you’ll later initialize as ProDos partitions to use with your Apple IIe card. Otherwise, taking in to account the limitations above, and the “wasted space” if you have really large partitions filled with small files, it’s really up to you.

3.3 Initialize an image file

Assuming you’ve used one of my image files as your boot drive, or have a copy of the patched HD SC setup 7.3.5 on your image file:

1. Under Setup and Repair (was Utilities) folder you will find a copy of a patched version of HD SC setup 7.3.5 (Figure 2)
2. Run HD SC setup 7.3.5 (Figure 3), SCSI Device 0 will be selected (Device 5 on MAME).
3. Press the Drive button to select SCSI Device: 1 (or whichever Device you mounted your image under, likely Device 5 on MAME) (Figure 4)
4. Press the initialize button to initialize the device, a warning message will appear (Figure 5), followed by a prompt to provide a name for the drive
5. Press the partition button to partition your initialized drive.
6. Wait, may take some time depending on the size of the image file (especially for MAME)
7. Select custom (Figure 6)
8. HD SC setup will show you the default partitions it set up when it initialized the drive (Figure 7).
9. Remove/edit the partitions as you see fit.  If you plan to use an Apple IIe card I’d suggest setting up two 32Meg ProDOS partitions.

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3.4 Options for getting your real world drive/removable media initialized and partitioned

There are two main methods for getting your drive initialized and partitioned:

1. Connecting the drive you want to initialize and partition directly to your classic Macintosh system, then boot your system using one of the boot options I’ve previously listed (e.g. Floppy Drive, CD-ROM etc.) with the drive you want to initialize and partition attached as a secondary drive.
2. Connect your drive to a modern system, create an image based on that drive, then initialize and partition the image file (3.3 above), then write the image file back on to your drive.