Use of 2nd floppy controller on ISA \ VOGONS

Use of 2nd floppy controller on ISA

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First post, by eesz34

Posted on 2022-07-17, 15:12

eesz34 Offline

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I have a Pentium MB that has a floppy connector but am considering adding a 2nd controller on an ISA card. The ISA card has jumpers to set it to a different I/O address, but no BIOS, just s simple basic card.

Without getting to the why, I'll likely boot from the integrated controller (since I believe I can't boot from the ISA controller anyway but that's ok) and have a couple drives on the ISA card that won't have to be bootable.

Is there any way to get these drives on the ISA card detected in DOS? What about Win9X or NT, will that detect it or can it be added in setup?

Reply 1 of 5, by mkarcher

Posted on 2022-07-17, 15:39

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A standard mainboard BIOS only supports a single floppy controller, so you won't get it to work without specific drivers.

If you can just set the card to a different port address, but not a different IRQ (than 6) or a different DMA channel (than 2), you need a BIOS / driver that only ever enables one card at the time. This actually is a quite common setup, and IIRC the DOS drivers you can get to run the two extra drives, mentioned in https://www.seasip.info/VintagePC/floppies.html#dosextra both expect this setup, so you should be good to go when you follow the instructions on that site.

Reply 2 of 5, by eesz34

Posted on 2022-07-17, 16:26

eesz34 Offline

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mkarcher wrote on 2022-07-17, 15:39:

A standard mainboard BIOS only supports a single floppy controller, so you won't get it to work without specific drivers.

If you can just set the card to a different port address, but not a different IRQ (than 6) or a different DMA channel (than 2), you need a BIOS / driver that only ever enables one card at the time. This actually is a quite common setup, and IIRC the DOS drivers you can get to run the two extra drives, mentioned in https://www.seasip.info/VintagePC/floppies.html#dosextra both expect this setup, so you should be good to go when you follow the instructions on that site.

I was able to find the DC2.SYS driver, so I may give this a try. Not sure if it's chip-specific, but they perhaps are all compatible.

Reply 3 of 5, by rmay635703

Posted on 2022-07-17, 16:58

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Someone should build a loadable rom for the DCS or GSC or similar quad floppy controllers that have the bios so you can add up to 4x 1.44mb floppies to any system

Reply 4 of 5, by Horun

Posted on 2022-07-17, 18:13

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That would be nice. I have a couple of bios driven 8bit floppy controllers, one a Joincom jc-1100 rev B1, the other is a DTK PII-151 v2. The Joincom allows setting as Secondary controller, not sure about the DTK.
Another driver for adding floppies under DOS is Wonder34.sys by Wonder Systems, it works similar to DC2 AFAIK.

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 5 of 5, by maxtherabbit

Posted on 2022-07-17, 18:20

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Pretty sure wonder34 is actually based on the same code base as DC2. Think it's a later revision

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