This article is relevant only to legacy hardware or software, and is retained for its historical significance.
Please ask at the community portal if you would like to update this article with current information.
How to mount beta 4-7 ramdisks
First unzip your IPSW, and take out the ramdisk file. It will be around 18MB. Then put it on your desktop.
Then type the following:
cd Desktop echo `hexdump -s12 -n4 -e '"%d\n"' ramdisk-should-just-be-a-bunch-of-numbers.dmg ` / 32 | bc
A number should appear. For example, in the case of beta 5, it would be 604800.
So you will type the following command now:
dd if=ramdisk-name-aka-a-bunch-of-numbers.dmg of=ramdiskb5.dmg bs=32 skip=1 count=**NUMBERS-GO-HERE** conv=sync
After this, you will have a file called ramdiskb5.dmg on your desktop. Just double click this file and it should mount fine. Example: Beta 5 Ramdisk
Macintosh:~ xxxxxxxxx$ cd /Users/xxxxxxx/Desktop/iPhone1,1_2.0_5A274d_Resto
This is where I unzipped my IPSW. I was a bit sloppy and did it the quick but annoying way, and accidently deleted some letters. But my point is that this is a folder name. You'd probably be better off just unzipping the ramdisk to your desktop rather than to a folder)
Macintosh:iPhone1,1_2.0_5A274d_Resto xxxxxxx$ echo `hexdump -s12 -n4 -e '"%d\n"' 018-3615-6.dmg ` / 32 | bc 604800
This gets me the number I need for the next step / 604800 this is the number I need for the next command
Macintosh:iPhone1,1_2.0_5A274d_Resto xxxxxxxx$ dd if=018-3615-6.dmg of=ramdiskb5.dmg bs=32 skip=1 count=604800 conv=sync 604800+0 records in 604800+0 records out 19353600 bytes transferred in 5.721840 secs (3382408 bytes/sec)
This made my ramdisk mountable At this point, the decrypted ramdisk was on my desktop, ready for use