Question Hard Drives not showing up in boot order

[NomarHayt]

my XPx64 computer crapped out, so i bought an identical one that came with win10pro instead.

i pulled out the DVD player and swapped it with my previous XP HDD... so the DEVICE CONFIGURATION in my BIOS's STORAGE tab sees both HDDs, but when i slide down 3 places to BOOT ORDER, it only sees whichever drive is connected to what appears to be the "primary" slot on my board. pretty frustrating considering that if I had left the DVD player there, the BOOT ORDER would show "DVD" as a boot option (but now that I have an HDD in its place, its not recognizing the HDD as a boot, even though it recognizes that an HDD is there)

ideally i want both drives to show on the screen during startup, then i want to choose XP or 10, but ill settle for both drives in the BOOT ORDER (because i can just go into BIOS before i start if i ever want to switch to the other one)

PLEASE REPLY IN EXTREMELY CONDESCENDING STEP-BY-STEP BABY TALK, assuming i know NOTHING about computers

 

[WaltzWorker]

You're dancing on a legal line here... I'm thinking that XP was bonded to the machine that died... Look for multiboot setup.

 

[mdd1963]

it's also possible the other PC is/was set to secure boot, in which case it would effectively not see your old XP installation as a viable boot device...

(Why you'd ever want deprecated Windows XP instead of WIn10Pro anyway is an entire different matter...)

 

[NomarHayt]

You're dancing on a legal line here... I'm thinking that XP was bonded to the machine that died... Look for multiboot setup.

need to edit my post to include: "Please talk to me like I'm 3 yrs old"

where do i look for "multiboot setup."

licensing is for one machine at a time, which I'm doing, as opposed to manipulating an activation code to use multiple machines simultaneously, with a single OS disc, which Im not doing
MS offers zero support for XP, i couldnt buy a new license from them even if i did need to, they wont sell me one

 

[NomarHayt]

it's also possible the other PC is/was set to secure boot, in which case it would effectively not see your old XP installation as a viable boot device...

(Why you'd ever want deprecated Windows XP instead of WIn10Pro anyway is an entire different matter...)

where would i find "secure boot" and how do i disable or change it

 

[NomarHayt]

yall are killin me!