DOS ain't dead - Can floppy work in nonDMA mode under DOS/Linux/Windows?

RayeR

CZ,
02.12.2017, 21:11

Can floppy work in nonDMA mode under DOS/Linux/Windows? (Developers)

Hi,
as I mentioned about LPC here some time ago I have some progress on my project of LPC bus SuperIo expander http://rayer.g6.cz/hardware/lpc_sio.htm
I'm waiting for a PCB from China now.
The question is if and how various OS can work with floppy controller when SuperIO is set to nonDMA mode (I assume that I will be able to configure it for usual legacy IO address so only difference will be in DMA because TPM header doesn't have LDRQ# signal routed on a pin). Is there some kernel config or patches at least for Linux?
I know that HW part is quite easy but FW/SW work will be more complicated. It's just a testing prototype nd challenge for me to make floppy live again in a modern PC (no I don't like floppy on USB).

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DOS gives me freedom to unlimited HW access.

Laaca

Czech republic,
03.12.2017, 22:50

@ RayeR

Can floppy work in nonDMA mode under DOS/Linux/Windows?

Post reply

I don't know whether BIOS uses the DMA transfers in diskette access (I suppose that probably yes) but they definitely must exist some low level utilities which handle the diskette access directly via I/O ports interface.
Try f.e. RESQFLPY on BTTR software archive (http://www.bttr-software.de/freesoft/disk2.htm)

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DOS-u-akbar!

RayeR

CZ,
04.12.2017, 02:03

@ Laaca

Can floppy work in nonDMA mode under DOS/Linux/Windows?

Post reply

> but they definitely must exist some low level
> utilities which handle the diskette access directly via I/O ports
> interface.
> Try f.e. RESQFLPY on BTTR software archive
> (http://www.bttr-software.de/freesoft/disk2.htm)

Yes I remember tools like HDcopy and probably Norton Utilities also handle floppy on it's own instead of BIOS but I don't know if they use DMA. I think it's not problem to write my own tool that will not use DMA but it's matter for compatability with old SW.

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DOS gives me freedom to unlimited HW access.

bretjohn

Rio Rancho, NM,
04.12.2017, 19:54

@ RayeR

Can floppy work in nonDMA mode under DOS/Linux/Windows?

Post reply

> but it's matter for compatability with old SW.

I don't think most software, even the old stuff, uses direct I/O or DMA access anyway. Most programs either depend on DOS (A: or B:) or the BIOS (INT 13h) to access disks, including floppies. I do remember some of the old hard drive backup utilities that used floppies as the backup media used DMA, though I don't remember if they actually _required_ it. I don't remember many other programs even trying to use it. I suppose some games might try to use it too, if they could run off floppies and needed the extra speed.

In my DOS USB disk driver (which also supports USB floppies), I didn't worry about emulating low-level I/O access. Virtualizing I/O is very difficult to accomplish in DOS, and rarely worth the effort. The only program where I've seen a real need to do it is in my USB joystick driver, since almost all programs use direct I/O access for joysticks instead of using the BIOS.

RayeR

CZ,
05.12.2017, 02:27

@ bretjohn

Can floppy work in nonDMA mode under DOS/Linux/Windows?

Post reply

Thaks for info, so seems most of DOS SW should work. And how about Windows? I thing that Win9x didn't use DMA - I remember that when you was copying a floppy the OS was mostly hanged until it finished but WinNT-based may use DMA as they are operable during copying...

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DOS gives me freedom to unlimited HW access.