ISA ( PC ) 8" floppy disk CONTROLLER ???

Chuck Guzis cclist at
Wed Feb 4 10:45:30 CST 2015

On 02/04/2015 06:03 AM, GerardCJAT wrote:
> For an OLD PC  ( ISA slot )  obviously ....
> Does this "beast" ever existed ??
> Does anyone recall some manufacturer's name ??
> Have I any chance to find one on Ebay or other at this time ??
> Or is "DBIT" adapter the only way to go ?

Of course there were/are!  All versions of the Microsoft Compaticard (I, 
II, IV) have 8-inch support, though I'd recommend only the IV, since, 
the I and II use a non-standard method of switching data rates. 
Microsoultions even sold 34-to-50 position adapters.

And really, that's all that's needed--a wiring change.  The CC manual 
even includes a call-out for the change.  I included a similar one in 
the 22Disk documentation.

The Sysgen Omnibridge explicitly supported 8" drives and the new XT-FDC 
project on Erik's Vintage Computer forum even features a 50-position 

In fact, if your FDC supports single-density (FM) modulation and 
high-density ("1.2M" and "1.44M" drive support), there's no reason why 
you need a separate floppy controller.   You can download Dave 
Dunfield's TestFDC program to test your system.

The DBIT widget is useful in that it includes an MCU that synthesizes 
the RWC/TG43 signal that some 8" drives need for writing, but not all 
do.  Microsolutions supplies this signal via a separate latch on the CC.


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