Hello, I'm a newbie, but I'm posting first on this forum because my question relates to Linux on a laptop. I've spent a lot of time looking over other postings here, but I haven't found one sufficiently similar to my situation. I also checked the search box for similar threads but they are not the same.

I recently (apparently) successfully installed Mint 21, “Vanessa” Cinnamon on my HP 6530b laptop using a live USB flash drive. Following the online download, I did both verification procedures before using Etcher to put it on the flash drive. Before the installation I set the laptop boot order to make the USB drive first. During the installation I accepted all the default settings including the partitioning.
The Mint installation went onto a new, unformatted 256GB solid state hard drive that I put into the laptop to replace the previous disk hard drive. At the end of the installation I removed the flash drive as prompted, but when the laptop tried to reboot, I got this message: “Non-system disk or disk error.”

Searching through the laptop's pre-boot controls, I discovered that UEFI booting could be enabled via the Device Configuration menu. Doing so brought up an HP warning that this setting was not recommended because it was still in development. (The HP 6530b laptop was introduced in 2008.)
Nevertheless, with UEFI enabled I was able to boot Mint successfully using F9 at startup to initiate the Boot Device Options menu and choosing Boot From EFI File, then a single option NO VOLUME LABEL, [Acpi (PNP0A03,0) /Pci(1F|2)/Ata(Primary,Master)/HD(Part2,Sig1CEF87D0-D67A-41DD-A425-20000CC4D241)], then single option <EFI>, then either <ubuntu> or <BOOT> (both work), then either grubx64.efi or shimx64.efi (both work).

With Mint booted I seem to be able to use all its features and applications that I have tried so far, including gParted to check the partitioning and the boot files. The first partition is /dev/sda1 using a grub2core.img file system, 1MiB in size and flagged bios_grub. The second partition is /dev/sda2, named EFI System Partition, using a fat32 file system mounted at /boot/efi using 6.27MiB of an available 513MiB and flagged boot,esp. The third partition is /dev/sda3, with an ext4 file system, using 23.37 GiB of an available 237.97GiB. All this seems correct compared with instructions I have found online.

I can also boot Mint from the USB Mint installation flash drive (without additional keystrokes), but it operates more slowly than using Mint from the SSD.

So what's my problem? Well, I would prefer to have Mint boot up automatically when I turn on the laptop instead of having to go through all those steps in the boot options choice. Note that this is not a dual boot issue. Although the laptop's previous OS was Windows 10, it was removed when I took out the old hard drive. I installed Mint only after the new SDD was in place.

My impression at this point is that somehow the HP firmware can't find or recognize the Mint bios_grub file. I'm hoping that someone out there has experience with an HP 6530b laptop or another laptop of similar vintage. Maybe there's a setting I could change or a programming workaround?
Thanks,
SyncOrSwm

I do not use LM but it looks more like an installer issue. The installer is assuming you know you want an EFI partition. But you do not.

1) Before booting up the LM stick....change bios back to legacy mode, no mention of UEFI please

I suggest you boot up the live product again and use

to delete all partitions. I suggest you create only 2 partions after deleting them and after clicking tick

a) you may have accidently created a partition table with GPT....you need to choose msdos

gparted -> device -> create new partiton table and choose msdos

https://imgur.com/ZBuvPG4

The image is for a usb stick /dev/sdc....ignore sdc its just an image example

2) create new partition on ssd say 250G as ext4
create another partition but choose swap for the balance it will be about 4G
click the tick to apply

3) when you redo the install....the install is supposed to offer to "something else"
there is a discussion about this install option here
https://forums.linuxmint.com/viewtopic.php?t=362954

If no mention of something else....you choose manually and choose to install to /dev/sda1
and choose /dev/sda2 as your swap partition

4) Watch carefully the naming of your devices. The internal SSD should be /dev/sdA
and with LM stick is should be /dev/sdB

so when installer offers to install a bootloader choose /dev/sda and it may also say MMR

good luck

Hello aus9
I am trying out your suggestion and all went smoothly and the choices offered were as you described, including the 'something else' option when I redid the install from the live LM flash drive. However, when I get to the window for the choice of partitions for the install, the Install button (lower right) remains disabled (greyed out) no matter which partition is highlighted. Of course I would only click on Install when sda1 is selected. Is there something else I need to highlight or click in that installation window to get it enabled?
Thanks and I welcome anyone else's ideas.

highlight /dev/sda1, click change, use as ext4, format, mountpoint /
highlight /dev/sda2, click change, use as swap

Hello colorpurple21859, aus9 and anyone else:
When I click Change, only option regarding ext4 is Ext4 journaling file system. Is that what I should select? Also, what should I select as the mount point? Options shown are /, /boot, /home, /tmp, /usr, /var, /srv, /opt and /usr/local. Or should I leave it blank?
Thanks.

Also, What should I select for 'Device for boot loader installation'? Is that the device where the new LM OS is to be placed or is that the device doing the installation?

select these:
Ext4 journaling file system
/
/dev/sda

Thank you, aus9 and colorpurple21859!
I followed all your instructions and now my old HP laptop boots from BIOS. A note to anyone else who might be interested: When I installed the two partitions and their settings as advised, I got a couple warning messages from Linux. One said that without efi in a partition the LM installation might fail and the other said that without a file structure designated the installation might fail. However, all was well.