Please note that you no longer have to do this part yourself! You can simply download pre-made blank formatted CHD images here from Arbee's site.
You will need some file prior to get into this tutorial
Minimum Recommended Version is Revision 9050 (Some revisions after the 0139u2 milestone)
Go to this page for more information
Since the patched one fail at Initializing really big HDs, you must have the original Apple Tool found on the 2nd installation floppy of System 6 (see here for the detailed instructions)
You need a patched version of the “Apple HD SC” tool since the original one will not work with bigger hard drives. You can get it here :
you can use "The Unarchiver" which is a tool for Mac and PC (as a beta under the name “unar”) to perform SEA Decompression.
At one point in this tutorial, you will have to copy a file from your real computer to an image. To this end I use BasiliskII since it got a handy “sharing” function. Yet, you will need a working installation of BasiliskII with a functional OS in it.
HFVExplorer seems to be an alternative for getting things done, yet I can't test this method right now. Feel free to expand this part if you can.
chdman extracthd -i macsehd.chd -o macsehd.dmg
chdman createhd -c none -i macsehd.dmg -o macsehd.chd
Now You'll be able to format bigger drive images directly from your Mac SE.
First you need to create a new CHD using chdman. You have to use the right parameter for chdman how many Cylinders, Heads and Sectors you want. You can use this tool to figure out.
Note that depending on which OS you want to run, there is volume limitations. For instance, after System 6 and before System 7.5 the limitation is 2GB. Starting with 7.5 the limitation is raised up to 4GB.
chdman createhd -c none -chs 8000,16,64 -o newmachd4gb.chd
The result will be a 4GB Hard Drive image. Some another examples :
-chs 1400,16,64 : for a 700MB Hard Drive image
-chs 4000,16,64 : for a 2GB Hard Drive image
-chs 8000,16,64 : for a 4GB Hard Drive image (OS 7.5 only. see above)
mess macse -hard1 macsehd.dmg -hard2 newmachd4gb.chd -ramsize 4M
If you have a fast forward key, just go for it
Last step is to make the whole disk enabled (at this time only some MB are usable)
You have now a valid CHD suitable for MESS, and that can be exported for use in Basilisk (Here for more about that).
Here’s a set of already formatted and partitioned blank Mac hard disk images (.CHD). Big thanks goes to Grégoire Duval and Arbee.