Thanks again Wonko for replying
Ok, sorry for not doing this earlier, but here are the real numbers from gparted. I'd upload the pic of it, but don't see a way to do that.
/dev/sda1 fat32 /boot/efi 100mb
/dev/sda2 ntfs Win7 149.90 gb
/dev/sda3 MS reserved 128mb
/dev/sda4 ntfs Win8.1 149.88gb
/dev/sda5 ntfs Win 11 120gb
I think Windows 8.1 created the reserved partition, though I wasn't paying attention.
Here is the output of gdisk which I already had:
gdisk64 -l \\.\physicaldrive0
GPT fdisk (gdisk) version 1.0.9
Partition table scan:
BSD: not present
APM: not present
Found valid GPT with protective MBR; using GPT.
Disk \\.\physicaldrive0: 3907029168 sectors, 1.8 TiB
Sector size (logical): 512 bytes
Disk identifier (GUID): 5F6B6028-1F8A-11ED-ADBC-14DDA912F7AB
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 3907029134
Partitions will be aligned on 2048-sector boundaries
Total free space is 3026225261 sectors (1.4 TiB)
Number Start (sector) End (sector) Size Code Name
1 2048 206847 100.0 MiB EF00
2 206848 314574847 149.9 GiB 0700
3 314574848 314836991 128.0 MiB 0C01 Microsoft reserved ...
4 314836992 629147647 149.9 GiB 0700 Basic data partition
5 629147648 880805887 120.0 GiB 0700 Basic data partition
I specifically used GPT, and during install, Windows 7 tried to MBR the disk, so I booted Hiren's CD and used the mbr2gpt utility in Win10 to convert it. I see it still says "w/protective MBR", but don't know if that matters with what I'm doing.
When you say the GPT partition table has to be reversed at the end of the disk, do you mean all the bytes are backwards in the sector compared to the main copy at the front of the disk?
Well, it looks like I have to wipe the disk anyway. I installed Linuxmint on a flash drive (to use as my maintenance disk), and I forgot that the Linuxmint install program ALWAYS seems to write grub to the 1st HDD no matter what. So I can no longer boot anything because I do not know grub, and have not been able to figure it out so far. I should have use plain Ubuntu.