Booting from External Drive

[thewall]

I have a HD with El Capitian which it took out of a white Mac book, can i boot up my iMac late 2014 running Big Sur from this HD and use all the features used by El Capitian, will i see the same desktop as i did on the MacBook, why i want to do this is that i have some programs that won't work on Big Sur.
If i can boot up from the HD will i be able to load my programs via a disc drive.

 

[Fishrrman]

According to everymac.com, the 2014 iMac came from the factory with OS 10.9.3.

So... YES... you should be able to boot the 2014 with the external drive with a bootable copy of El Cap on it.

Why don't you just connect it and try it?

If you don't have an enclosure yet, you might consider this one:

SABRENT 2.5 Inch SATA to USB 3.0 Tool Free External Hard Drive Enclosure [Optimized for SSD, Support UASP SATA III] Black (EC-UASP)

SABRENT 2.5 Inch SATA to USB 3.0 Tool Free External Hard Drive Enclosure [Optimized for SSD, Support UASP SATA III] Black (EC-UASP)

www.amazon.com