SomeGuy
Veteran Member
I decided to test the "legacy" compatiblity of several recent motherboards I acquired. The results were rather interesting.
All of the boards tested could successfully emulate PS/2 hardware compatiblity with a USB keyboard. However, I could not get USB mice to emulate PS/2 hardware compatiblity. (It's probably not supposed to, but they don't tell you that!)
I also tested a USB floppy drive in combination with the real floppy drive to determine BIOS drive behavior. Each mapped the USB floppy as B: when a real floppy drive was present, unless it booted from the USB floppy. In that case the USB floppy became A: and the real drive became B:
In testing, I also noticed that BIOS does not support low-level formatting disks in USB Floppy drives. All format calls do nothing and return "successful". It is also worth noting here that most USB floppies, including the one I tested with, do not support 720k disks or formats that deviate from the common 1.44mb format.
Each of these boards only support ONE floppy disk drive. Attaching a second drive in the standard way will do nothing. It wouldn't be too hard to wire up a manual switch to switch between drives, but the mind boggles as to why they would leave that out.
I also tested compatiblity with a copy (sorry, not an original) of IBM PC-DOS 1.00 on both 5.25" and low density 3.5" disks, and booting an original copy-protected Pinball Construction Set 5.25" disk. Several of the AMI bioses require the "55AA" ID at the end of the boot sector, which DOS 1.00 and early booters lack. Booting Pinball Construction Set or similar also tests the ability of the system to handle floppy disk copy protection.
My primary goal was to test floppy disk compatiblity, as such I did not extensively test COM or LPT ports. All COM and LPT ports appeared as standard ports to DOS diagnostics.
For formatting tests, I used both the DOS formatter and NFORMAT.
Gigabyte GA-870A-UD3
--------------------
Bios: Award
Supports a SINGLE 2.88mb, 1.44mb, 1.2mb, 720kb, or 360k floppy drive with "Mode 3" option.
Other: SINGLE PS/2 port, one COM header, LPT header, IDE.
Note: The the single PS/2 port can be used with either a keyboard or a mouse, but is not wired for use with a splitter.
Setup: Must specify FDD type in the BIOS.
TestFDC:
250K SD - Fail
250K DD - Pass
250K DD/128 - Fail
500K SD - Fail
500K DD - Pass
500K DD/128 - Fail
General Format/Read/Write tests:
1.44mb (1.44mb and 720k media) - OK
720k - OK
1.2mb (1.2mb and 360k media) - OK
360k - OK
Formats/Reads/Writes 1.7mb disks in 1.44mb drive (21 sectors per track) - OK
Note: Requires FDREAD or BIOSPTCH under DOS 6.22 or earlier.
Boots DOS 6.22: Yes
DOS 6.22 Backup test: Passed
Boots unmodified DOS 1.00 (on 5.25" and 3.5"): Yes
Boots Pinball Construction Set 5.25" disk: Yes.
ASRock 880GM-LE FX
------------------
Bios: AMI
Supports a SINGLE 2.88mb, 1.44mb, 1.2mb, 720kb, or 360k floppy drive.
Other: PS/2 mouse port, PS/2 keyboard port, one COM header, LPT header, IDE.
Setup: Must specify FDD type in the BIOS.
TestFDC:
250K SD - Pass!!
250K DD - Pass
250K DD/128 - Fail
500K SD - Pass
500K DD - Pass
500K DD/128 - Fail
General Format/Read/Write tests:
1.44mb (1.44mb and 720k media) - OK
720k - OK
1.2mb (1.2mb and 360k media) - OK
360k - OK
Formats/Reads/Writes 1.7mb disks in 1.44mb drive (21 sectors per track) - OK
Note: Requires FDREAD or BIOSPTCH under DOS 6.22 or earlier.
Boots DOS 6.22: Yes
DOS 6.22 Backup test: Fails (Seems to fail writing the second disk)
Boots unmodified DOS 1.00 (on 5.25" and 3.5"): No - This bios requires the "55AA" boot ID on the boot sector.
Boots modified DOS 1.00 (on 5.25" and 3.5"): Yes
Boots Pinball Construction Set 5.25" disk: No.
BIOSTAR A770E3
------------------
Bios: AMI
Supports a SINGLE 2.88mb, 1.44mb, 1.2mb, 720kb, or 360k floppy drive.
Other: PS/2 mouse port, PS/2 keyboard port, one COM port, LPT header, IDE.
TestFDC:
250K SD - Fail
250K DD - Pass
250K DD/128 - Fail (And hangs!)
500K SD - Fail
500K DD - Pass
500K DD/128 - Fail
General Format/Read/Write tests:
1.44mb (1.44mb and 720k media) - OK
720k - OK
1.2mb (1.2mb and 360k media) - OK
360k - OK
Formats/Reads/Writes 1.7mb disks in 1.44mb drive (21 sectors per track) - OK
Note: Requires FDREAD or BIOSPTCH under DOS 6.22 or earlier.
Note: Behaves strangely if not power cycled after changing the bios drive type.
Boots DOS 6.22: Yes
DOS 6.22 Backup test: Fails (Seems to fail writing the second disk)
Boots unmodified DOS 1.00 (on 5.25" and 3.5"): No - This bios requires the "55AA" boot ID on the boot sector.
Boots modified DOS 1.00 (on 5.25" and 3.5"): Yes
Boots Pinball Construction Set 5.25" disk: No.
ASRock 990FX Extreme 4
----------------------
Bios: AMI UEFI
Supports a SINGLE 1.44mb floppy drive.
Other: PS/2 mouse port, PS/2 keyboard port, one COM header, IDE.
Note: There is no way to specify any drive type other than 1.44mb! (Or at least I can't find one)
Note: Lacks an LPT port.
Note: A vesa video mode test failed, even though this was the same video card used on the Gigabyte board tests.
TestFDC:
250K SD - Pass!!
250K DD - Pass
250K DD/128 - Fail
500K SD - Pass
500K DD - Pass
500K DD/128 - Fail
General Format/Read/Write tests:
1.44mb (1.44mb and 720k media) - OK
720k - Fail (no support!?)
1.2mb (1.2mb and 360k media) - Fail (no support!?)
360k - Fail (No Support!?)
Formats/Reads/Writes 1.7mb disks in 1.44mb drive (21 sectors per track) - OK
Note: Requires FDREAD or BIOSPTCH under DOS 6.22 or earlier.
Boots DOS 6.22: Yes
DOS 6.22 Backup test: Pass
Boots unmodified DOS 1.00 (on 3.5"): Yes
Note: You can connect a 720k, 1.2mb, or 360k drive with varying levels of success but OSes will assume it is a 1.4mb drive. I did get it to boot DOS 1.00/PBCS from 360k but the BIOS forces a seek test at boot that the 360k drive doesn't really like. Some tools like ImageDisk and NFORMAT can be configured to ignore the BIOS settings, but standard tools may fail. Under DOS 6.22 you may be able to use the DRIVEPARM command to work around the lack of bios support. (But really, WTF?)
I also verified the FDC chip can do 300K bps, but forgot to run TestFDC on the 1.2mb drive tests.
On a side note, their graphical BIOS setup is ugly, and they advertise it as if it were a brand new invention.
Also, interestingly, even though this is a UEFI BIOS there was no mention of "secure boot" in the version shipped with the board. An update adds secure boot but it is disabled by default. - Somehow I don't think IBM PC-DOS 1.00 is digitally signed
Conclusion
-----------
Each of these boards has its pros and cons with regard to legacy support. Over all, the Gigabyte board and the Award BIOS feels much more "solid" than the others, but the lack of a second PS/2 port is a drawback.
I was greatly surprised that that the 990FX and the 880GM-LE FX could read/write single density modes. Note that it is possible this ability may vary from board to board if they use different IO chips.
If there is some trick to set the drive type in the 990FX, that would be a winner simply for being the latest model with an FDC that I could find. (And a bonus for supporting SD!). It lacks an LPT, but has plenty of PCI/PCIe expansion for a Serial/Parallel card.
All of the boards tested could successfully emulate PS/2 hardware compatiblity with a USB keyboard. However, I could not get USB mice to emulate PS/2 hardware compatiblity. (It's probably not supposed to, but they don't tell you that!)
I also tested a USB floppy drive in combination with the real floppy drive to determine BIOS drive behavior. Each mapped the USB floppy as B: when a real floppy drive was present, unless it booted from the USB floppy. In that case the USB floppy became A: and the real drive became B:
In testing, I also noticed that BIOS does not support low-level formatting disks in USB Floppy drives. All format calls do nothing and return "successful". It is also worth noting here that most USB floppies, including the one I tested with, do not support 720k disks or formats that deviate from the common 1.44mb format.
Each of these boards only support ONE floppy disk drive. Attaching a second drive in the standard way will do nothing. It wouldn't be too hard to wire up a manual switch to switch between drives, but the mind boggles as to why they would leave that out.
I also tested compatiblity with a copy (sorry, not an original) of IBM PC-DOS 1.00 on both 5.25" and low density 3.5" disks, and booting an original copy-protected Pinball Construction Set 5.25" disk. Several of the AMI bioses require the "55AA" ID at the end of the boot sector, which DOS 1.00 and early booters lack. Booting Pinball Construction Set or similar also tests the ability of the system to handle floppy disk copy protection.
My primary goal was to test floppy disk compatiblity, as such I did not extensively test COM or LPT ports. All COM and LPT ports appeared as standard ports to DOS diagnostics.
For formatting tests, I used both the DOS formatter and NFORMAT.
Gigabyte GA-870A-UD3
--------------------
Bios: Award
Supports a SINGLE 2.88mb, 1.44mb, 1.2mb, 720kb, or 360k floppy drive with "Mode 3" option.
Other: SINGLE PS/2 port, one COM header, LPT header, IDE.
Note: The the single PS/2 port can be used with either a keyboard or a mouse, but is not wired for use with a splitter.
Setup: Must specify FDD type in the BIOS.
TestFDC:
250K SD - Fail
250K DD - Pass
250K DD/128 - Fail
500K SD - Fail
500K DD - Pass
500K DD/128 - Fail
General Format/Read/Write tests:
1.44mb (1.44mb and 720k media) - OK
720k - OK
1.2mb (1.2mb and 360k media) - OK
360k - OK
Formats/Reads/Writes 1.7mb disks in 1.44mb drive (21 sectors per track) - OK
Note: Requires FDREAD or BIOSPTCH under DOS 6.22 or earlier.
Boots DOS 6.22: Yes
DOS 6.22 Backup test: Passed
Boots unmodified DOS 1.00 (on 5.25" and 3.5"): Yes
Boots Pinball Construction Set 5.25" disk: Yes.
ASRock 880GM-LE FX
------------------
Bios: AMI
Supports a SINGLE 2.88mb, 1.44mb, 1.2mb, 720kb, or 360k floppy drive.
Other: PS/2 mouse port, PS/2 keyboard port, one COM header, LPT header, IDE.
Setup: Must specify FDD type in the BIOS.
TestFDC:
250K SD - Pass!!
250K DD - Pass
250K DD/128 - Fail
500K SD - Pass
500K DD - Pass
500K DD/128 - Fail
General Format/Read/Write tests:
1.44mb (1.44mb and 720k media) - OK
720k - OK
1.2mb (1.2mb and 360k media) - OK
360k - OK
Formats/Reads/Writes 1.7mb disks in 1.44mb drive (21 sectors per track) - OK
Note: Requires FDREAD or BIOSPTCH under DOS 6.22 or earlier.
Boots DOS 6.22: Yes
DOS 6.22 Backup test: Fails (Seems to fail writing the second disk)
Boots unmodified DOS 1.00 (on 5.25" and 3.5"): No - This bios requires the "55AA" boot ID on the boot sector.
Boots modified DOS 1.00 (on 5.25" and 3.5"): Yes
Boots Pinball Construction Set 5.25" disk: No.
BIOSTAR A770E3
------------------
Bios: AMI
Supports a SINGLE 2.88mb, 1.44mb, 1.2mb, 720kb, or 360k floppy drive.
Other: PS/2 mouse port, PS/2 keyboard port, one COM port, LPT header, IDE.
TestFDC:
250K SD - Fail
250K DD - Pass
250K DD/128 - Fail (And hangs!)
500K SD - Fail
500K DD - Pass
500K DD/128 - Fail
General Format/Read/Write tests:
1.44mb (1.44mb and 720k media) - OK
720k - OK
1.2mb (1.2mb and 360k media) - OK
360k - OK
Formats/Reads/Writes 1.7mb disks in 1.44mb drive (21 sectors per track) - OK
Note: Requires FDREAD or BIOSPTCH under DOS 6.22 or earlier.
Note: Behaves strangely if not power cycled after changing the bios drive type.
Boots DOS 6.22: Yes
DOS 6.22 Backup test: Fails (Seems to fail writing the second disk)
Boots unmodified DOS 1.00 (on 5.25" and 3.5"): No - This bios requires the "55AA" boot ID on the boot sector.
Boots modified DOS 1.00 (on 5.25" and 3.5"): Yes
Boots Pinball Construction Set 5.25" disk: No.
ASRock 990FX Extreme 4
----------------------
Bios: AMI UEFI
Supports a SINGLE 1.44mb floppy drive.
Other: PS/2 mouse port, PS/2 keyboard port, one COM header, IDE.
Note: There is no way to specify any drive type other than 1.44mb! (Or at least I can't find one)
Note: Lacks an LPT port.
Note: A vesa video mode test failed, even though this was the same video card used on the Gigabyte board tests.
TestFDC:
250K SD - Pass!!
250K DD - Pass
250K DD/128 - Fail
500K SD - Pass
500K DD - Pass
500K DD/128 - Fail
General Format/Read/Write tests:
1.44mb (1.44mb and 720k media) - OK
720k - Fail (no support!?)
1.2mb (1.2mb and 360k media) - Fail (no support!?)
360k - Fail (No Support!?)
Formats/Reads/Writes 1.7mb disks in 1.44mb drive (21 sectors per track) - OK
Note: Requires FDREAD or BIOSPTCH under DOS 6.22 or earlier.
Boots DOS 6.22: Yes
DOS 6.22 Backup test: Pass
Boots unmodified DOS 1.00 (on 3.5"): Yes
Note: You can connect a 720k, 1.2mb, or 360k drive with varying levels of success but OSes will assume it is a 1.4mb drive. I did get it to boot DOS 1.00/PBCS from 360k but the BIOS forces a seek test at boot that the 360k drive doesn't really like. Some tools like ImageDisk and NFORMAT can be configured to ignore the BIOS settings, but standard tools may fail. Under DOS 6.22 you may be able to use the DRIVEPARM command to work around the lack of bios support. (But really, WTF?)
I also verified the FDC chip can do 300K bps, but forgot to run TestFDC on the 1.2mb drive tests.
On a side note, their graphical BIOS setup is ugly, and they advertise it as if it were a brand new invention.
Also, interestingly, even though this is a UEFI BIOS there was no mention of "secure boot" in the version shipped with the board. An update adds secure boot but it is disabled by default. - Somehow I don't think IBM PC-DOS 1.00 is digitally signed
Conclusion
-----------
Each of these boards has its pros and cons with regard to legacy support. Over all, the Gigabyte board and the Award BIOS feels much more "solid" than the others, but the lack of a second PS/2 port is a drawback.
I was greatly surprised that that the 990FX and the 880GM-LE FX could read/write single density modes. Note that it is possible this ability may vary from board to board if they use different IO chips.
If there is some trick to set the drive type in the 990FX, that would be a winner simply for being the latest model with an FDC that I could find. (And a bonus for supporting SD!). It lacks an LPT, but has plenty of PCI/PCIe expansion for a Serial/Parallel card.