Introduction
- Note:This post is even more personal that is typical for me, i for quite long time wanted to write something like that, be aware and its full of hate (it doesnt mean that i would be too vulgar or something like that, you can hate something with dignity:).

- For me was always best thing on PC platform, its backwards compatibility that even on new machine, you could run even very old programs, without any or with some fiddling.
- I understand if something not supported, because is simply too slow for some program, game etc. Im also ok if there is physical HW incompatibility - ie you can use new cpu on old MB..
- What make me angry if someone proudly add to new features list, removing of some old compatibility features, its abomination, i always want to punch such guy / company, im completely ok to make it unsupported but still in package, especially evil companies use this to force people to upgrade.. and be victim constant upgrading spiral.. for example some new build of Win10 removed completely AGP support.
- not existing drivers are mixed bag, i usually understand companies not supporting older OSes, if there are not using of too much their, but there some exceptions, which are really dont like.. and its product is obsolete it would be nice release full documentation and make older driver open source, so someone can add support of new HW as its hobby project..

Beware of these compatibility breakers / barriers (work in progress):

1. no ISA slots, ISA slots are from gaming perspective good for ISA Sound cards, which are most compatible with DOS, workaround is use PCI slot Sound cards, with some legacy modes emulation drivers which are working various degree of success depends on sound card and its drivers, games and used MB chipset (south-bridge)
2. no PCI slots
3. no support for older PCI-E v1 Graphics card on PCI-E v3 boards
4. no PS/2 ports or one 1 PS/2 port which is not supporting P2/2 Y cable for 2 devices. There are some PCI P2/2 cards, but most user reporting, that they are not working at least not in Windows 98.
5. no serial port (mainly programmers care about them) and no Parallel ports, there some some PCI/PCI-E cards with these boards.
6. missing magic (undocumented or non listed in normal user specs) feature for support of PCI sound cards. There are some Z97 board with PCI slots, but PCI slots are not working there.
7. Voodoo 1/2/3 acceleration is not working with newer chipsets, i dunno why. Voodoo 3 is usually working fine in 2D mode, or in Windows 9x, but not with DOS Glide.
   Newest MB, there i made Voodoo 3 working was i865 chipset Asrock Conroe865PE MB.
8. too much RAM for Windows 9x and DOS which make these OS uninstallable or unbootable , there are limiters like HimemX or Burnmem, which are working with all MB where is tested it, for Windows 9x there are also paid rLoews patches
9. MB without IDE mode for storage controller (intel Z170, i dunno about Ryzen). Workaround is external PCI/PCIe controllers with IDE mode (some of them have special IDE) bios
10. even with some Sata controller in IDE mode is Windows 98 storage devices not working well (missing UDMA modes), solution is paid rLoews patch
11. filesystem limits (i would say design flaws) FAT16 max partion size 2 GB, FAT32 in theory is limited to 32GB, later was reported some problem with bigger partitions than 128 GB, but usually much bigger were working, once again rLoew have some patch(es) and claim that 4 TB FAT32 driver no problem with Windows 98. There is also FAT 32, max 1 filesize 4GB limit.
12. newer Graphics cards are started in very underclocked mode unless are overclocked by its drivers. Its nice from no noise perspective but, not from performance perspective, even Linux has this problem with open source Nvidia drivers.
13. some newer Graphics are card, have bugs in VESA implementation, so have glitches in pictures or Vesa modes are not working with them with universal Vesa drivers
14. we had to fiddle with MS-DOS conventional memory settings for Aeons because some idiot though that 640KB would be enough for everyone for eternity.
15. some new MB have botched BIOS so in 32bit OS you can see, no 3.x GB of RAM, but only 2GB, or 1,5 GB.. "winner" was one MSI X99 board, where i have 920 MB of ram in all 32 bit OSes include Win7 32bit, what experience, joke was that this OS was officialy supported.
16. some new MB only support PCIe v2 or v3 Videocards, but not v1, for example my new Z370 Gigabyte board, its probably chipset thing..
17. videocard bioses arent no backwards compatible so PCIe v3 cards not working on some MB..
18. some PCI videocards are not working with some MBs with PCI slots..
19. whole "forced" 32 to 64 bit Windows upgrade madness, there where already PAE solution for Windows XP, as is proven unofficial patch, but MS was lazy to force vendors to fix errors with their drivers to make them working with PAE.
20. missing 32bit to 64bit Windows upgrade.. Workaround there some migration utilities to backup data / apps / their setting and migrate them to new OS, but MS should to by its own, without workarounds.
21. USB 2/3 without backward compatible drivers for older OSes for USB 2/1.1..
22. not working fullscreen DOS mode in Windows 98 on Geforce 4-7 GPUs black screen bug
23. AMD + MS their unsupporting Ryzen on Windows 7, especially with Ryzen GPU in processor it is problem
24. Geforce 970/980/first Titan missing support for XP, which could be fixed by Ini files editation..
25. some major bugs in drivers, which are blocking use HW which should be supported, because someone ended product support before fix was made
26. Remember DX10 for Vista only? How much DX10 game we actually saw - only few with even fewer DX10 features.
27. Bioses with Whitelist of supported PCI devices - typical for some Notebooks - Lenovo,HP etc.. but some O.E.M machine use them too.
28. ATX PSU with weak 5V branch, which dont have enough power for some Athlon systems
29. IN AC97 specification is that any card with this standard should be DOS compatible, but its joke.
30. Intel HD audio is not backwards compatible with AC97, because Intel dont give a f..
31. Whole MBR 4 primary partitions limit and OSes which require to run on primary partition

You can report others, i could help people with some retro HW selection, i looking to add them to list we can hate them together..

Every hatelist need its hate song i like this one (completely unrelated except of hate).