PCI floppy controller

[Maciej W. Rozycki]

On Thu, 21 Apr 2022, Chuck Guzis via cctalk wrote:

> I suppose it might be possible to fashion a legacy floppy controller on
> a PCI card with enough supporting logic to make it compatible with
> existing software, but I'm not aware of such an effort.

 You can of course build a PCI FDD interface around the NEC uPD765 or an
equivalent controller, but you can't make it compatible with existing PC 
software, because too much PC specifics has been embedded there around the 
8237 DMA controller and DMA page registers at fixed port I/O locations, 
which is inherently incompatible with the PCI decoding model.

 A feasible solution is a SCSI FDD option, such as the DEC RX23 device
(which is actually a whole embedded microcomputer built around an 8080 CPU 
and using an 8237 DMA controller, an 8259 interrupt controller, a uPD765 
floppy drive controller and a 5380 SCSI interface), which works as a 
removable drive with any single-ended parallel SCSI host adapter, e.g.:

scsi 2:0:4:0: Direct-Access     DEC      RX23     (C) DEC 0054 PQ: 0 ANSI: 1 CCS

Such SCSI host adapters remain widely available as PCI and PCIe options.

 HTH,

  Maciej