Chkcpu wrote on 2023-10-25, 20:33:Hi analog_programmer, […]
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Hi analog_programmer,
I’m very pleased to hear you got the BX-6AP2 board running again! 😀
Horun wrote on 2023-10-24, 01:29:
Great ! Yeah I do not think support for more PCI slots in bios (more ISA definately not) will be an issue, no different than having board with 5 slots and only using 2, the other 3 will be scanned and find nothing/found empty.
In your case it will scan "empty slots". Only down side is in BIOS it may allow manual setting IRQs to PCI 4 and 5 but that won't effect anything except taking up those IRQ's as in use.....
Is worse if you use a 3 PCI only bios on a 4 PCI board, the bios may not scan that 4th slot making it unusable/unsettable IIRC.
I fully agree with Horun’s view on using the 5 PCI-slots BIOS on your 3 PCI-slots board.
However, with the Lucky Star 6VABX2 1.1/1.2 BIOS you may run into a snag when using the 3rd PCI-slot.
When you look into the i440BX BIOS for the Intel chipset version of your BX-6AP2 board with Modbin, you will see the following PCI Configuration:
BX-6AP2_PCI-slots.png
Although the BX-6AP2 has 3 PCI-slots, there are 5 entries in this table. The first entry for PCI-slot 00/Device nbr 01 is the PCI Bus master in the Northbridge and the second entry for PCI-slot 01/Device nbr 07 is for the PCI device in the Southbridge (IDE controller and USB controller).
Reading the remaining 3 table entries you get the Device numbers of the PCI-extension slots: 9 (09), 11 (0B), and 13 (OD). The programming of these PCI Device numbers in the BIOS must coincide with the actual hardware wiring of the address lines between the PCI-slots and the Northbridge on your board, otherwise the whole PnP function won’t work for that PCI-slot.
Now let’s assume the PCI-slots address wiring is the same on the VIA chipset version of the BX-6AP2 and when I look into the Lucky star 6VABX2C0 BIOS, I see this:
6VABX2-PCI-slots.png
For this 5 PCI-slot BIOS there are now 7 table entries, the first 2 again for the North- and Southbridge and the remaining 5 for the PCI Extension slots.
The device numbers for the extension slots are 8, 9, 10, 11, and 12 in this BIOS. Device numbers 9 and 11 are present, but 13 is not. So it is possible the 3rd PCI-slot on the BX-6AP2 won’t work with this Lucky star BIOS.
You can easily test this by putting a PCI-card like a NIC in PCI-slot 1 and check the PCI device listing on the second BIOS boot screen for detection of the card. Also device number 9, 11, or 13 should be assigned to the card and an IRQ number as well.
Then repeat this test with the card in slot 2 and slot 3.
Unfortunately the PCI device programming cannot be changed in Modbin.
I hope the original VIA BX-6AP2 BIOS will be found one day… 😉
Cheers, Jan
Thank you very much for your investigation in these differences, Jan. This is one good point. I appreciate the help you gave me together with the other fellow forum member - Horun.
I've only checked physically the first PCI slot with videocard and it receives IRQ according to settings in transplanted BIOS. So, I have to check the other two slots, but I'm pretty sure now, that third one will not work as expected with PnP cards.
And yes, this version of MODBIN for older Awars BIOSes can't change PCI table settings:
The attachment modbin_pci.jpg is no longer available
Yesterday I've created some custom BIOS from 6VABX2's and tested it. Here are the results:
The attachment POST_BOOT_MESSAGES.JPG is no longer available
The attachment POST_CONF.JPG is no longer available
On the second picture there is something that bothers me. I marked it in red rectangle. Why this "APCI controller" has IRQ assigned without bus number?
I'm thinking of editing the settings for the keyboard controller on the BIOSes (from Shuttle HOT-661V V1.x/2.x and for Soyo SY-V6BE+) that are blocking normal POST process because of a potential error related to its initialization, but possibly they'll have more appropriate settings for the PCI table. I've never tried this, so I don't know if it will help, but there's absolutely no problem to test it. This is from 6VABX2 BIOS:
The attachment keyboard_controller_type.jpg is no longer available
P.S. Problems with HDD detection were due to loose BIOS chip socket connections. FDD no read problem -I've no time for deeper investigation now as I don't need to use FD drive with this mobo right now.
Update: Just tried all three PCI slots with PnP 3Com NIC adapter. Yeah, there's no way to assign IRQ when is used the third PCI slot (no problems with first and second slot), so now I can 100% confirm Jan's assumption about partially working third PCI slot.
I'm thinking to try again the rejected partially POSTing BIOSes with edited keyboard adapter type setting through MODBIN. A good task for this weekend.
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