Installing amiga os 3.9 and amiga os 4.0 in the same hd

I know that this argument has already been discussed here..

I wish to install amiga os 3.9 and amiga os 4.0 on my amiga 1200 and mediator with ppc.. i know that i have to create the partitions inside or <- than 4 Giga. then i can create two or more partitions inside this size.. The question is, after i have installed both the operating system, how can i choose and boot the desired os ?.. i ask that because i don't know how many times i have to enter in the early startup-menu to select the boot device ( that because if you boot os4 on classic machine, it reset itself while booting, so i don't know if-when resetting it keeps the changing did in the early startupmenu or not )..

It could be possible, as alternative, to create a boot floppy to insert when turning on the computer to load the desired os ?.. One floppy for os4 and one floppy for the amiga os 3.9 ?.. the floppy would load the os choosing the hard disk.. would it be possible ?

thanks in advance for the help and the infos

@nubechecorre

UP !

@nubechecorre

The simplest way with out creating scripts and moving assigns is to have two <2GB partitions and make both bootable.

Install OS4.0 on the first partition.
Install OS3.9 on the second partition.

You can alternate this its your preference.

Give the 3.9 partition a boot PRI of 4 and 4.0 partition a boot pri of 3.

This way it will always default to OS3.9. I do this due to the multiple resets caused by blizkick, setpatch rom update etc etc before 3.9 boots.

Now for your 4.0 partiton. If for example you have it on DH1 boot pri 3.

Edit your Kickstart-AXXXX file in sys:kickstarts

add the line

MODULE Kickstart/Bootdevice

Now create a textfile in sys:kickstart called bootdevice to which the contents are the volume name of the drive with OS4.0 on.

Eg: a text file with just the following contents.

DH1

Now you can boot into 3.9 by default But to boot into 4.0 just go into the ESS menu on power up or on reset and select your 4.0 partition as the bootdevice. It won't matter that the 3.9 has a higher boot pri as the bootdevice config youve just created will force 4.0 to boot from your OS4.0 partition after the kickstart has loaded.

@Jurassicc

Thanks Mate ! thanks for this info that i didn't know You have simplified my life now

@nubechecorre

I forgot to mention you can boot directly from 3.9 to 4.0
without switching off or resetting.

Example:

If you have 3.9 on DH0: and 4.0 on DH1: and you hae booted into 3.9 to swap to 4.0 open a shell and type

CD DH1:
DH1:C/Bootloader Filename DH1:Kickstart/Kicklayout-axxxx


or make a script and give it an icon

where xxxx is 1200 or 4000 etc depending on your hardware.

@Jurassicc

What ?? is it true ?? so i can go into os4 mode directly from the wb of the amiga os 3.9 ? and when i reset the os it reload the os4 right ?

wow it reminds me the commodore 128 where in the basic you wrote go 64 to go into 64 mode

Man you are great and the os4 team too

@nubechecorre

Filename is an AMIGA DOS command ?