Get some of these to move the drive around: https://www.startech.com/en-us/hdd/drw110atabk

If you have a drive larger than 512MB, you will likely want to put EZ-drive on it so that all systems recognize the storage with the same geometry.

It's not too hard to move drives between systems if you are just using DOS. You can use a dos boot menu to start with different configurations if you need different config.sys and autoexec settings.

If you put Win95 or Win98 on it, maybe you can do some fancy footwork to do different hardware profiles, but that's going to be hard.

You would likely want to install multiple copies of Win9x in different directories and set up a dos boot menu to let you select the correct installation.

i can’t use rhis type ok equipment because i have onyl one 5,25 slot and i need it for cd-rom or floppy 5,25. i am able to use a cf on the backside, using a bracket for pci or isa slot, i am looking for a way to use a regular 2,5” hard disk instead

In the past I have experimented with this too.
I led a ribbon cable and molex our thru the back of the computer.

The original boot disk was configured cable select. With no other device present it should be detected as master.
When a second disk was attached outside the case, jumped as master and was detected as so and the internal disk with cs was read as slave.
With your 2,5"disk you could use any 2,5-3,5 converter.

CD-ROM was connected to the secondary controller on one machine and the two others had none.

Alternatively you could look for a SCSI controller for each pc and make it the primary boot device. Then attach an external diskeenclosure and set it up to be bootable.

AlessandroB wrote on 2022-12-11, 13:08:

this computer only has an external 5.25 bay and I would like to use the cd-rom drives. I had thought of using compact flash mounted on the brackets of the expansion cards (yes ebay cost 5€ each) but I don't like the silence of the CF. So I thought there was some way to use the 2.5" ide disk but I don't see the practical and clean way to transport it from one computer to another every time. how can I do? tnks

-Buy a 5.25" to dual/triple slimline ODD adaptor frame.
-Buy a slimline IDE ODD and an adaptor board to regular IDE.
-Mount the slimline ODD into your 5.25" to dual/triple slimline ODD adaptor frame.
Buy this adaptor and cut out the front so you can slide your 2.5" HDD in and out. Attach some tape to the HDD to serve as a pulltab.
-Mount the adaptor into your 5.25" to dual/triple slimline ODD adaptor frame.
-Mount the whole thing into the 5.25" bay where currently your ODD is.

Thanks for the ingenious advice, but on my machines I prefer to stay as "retro" visually as possible" I'm afraid that apart from the scsi solution (which remains the cleanest) there are no other solutions other than using the cd-ide adapter. This:

Do you have a free 3.5" bay? Then you could use a 3.5" mobile rack for a 2.5" harddisk. I have never seen those for IDE-drives, but you could use an SATA drive and attach a SATA/IDE-converter internally